Computer Networking and Data Communication Solved Question Paper

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Compute r Networking a nd Da ta Communic a tion Solve d Que stion Pa pe r - slide pdf.c om

1. Define Network? A network is a set of devices connected by physical media links. A network is recursively is a connection of two or more nodes by a physical link or two or more networks connected by one or more nodes. 2. What is a Link? At the lowest level, a network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Link. 3. What is a node? A network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Links and the computer it connects is called as Nodes. 4. What is a gateway or Router? A node that is connected to two or more networks is commonly called as router or Gateway. It enerally forwards messae from one network to another. 5. What is point-point ink? If the physical links are limited to a pair of nodes it is said to be point!point link. !. What is "utipe #$$ess? If the physical links are shared by more than two nodes, it is said to be "ultiple Access. %. What are the ad&antages of Distri'uted (ro$essing? a. Security#$ncapsulation b. %istributed database c. &aster 'roblem solvin d. Security throuh redundancy e. (ollaborative 'rocessin ). What are the $riteria ne$essary for an effe$ti&e and effi$ient network? a. 'erformance It can be measured in many ways, includin transmit time and response time. b. )eliability It is measured by fre*uency of failure, the time it takes a link to recover from a failure, and the network+s robustness. c. Security Security issues includes protectin data from unauthoried access and virues. *. Na+e the fa$tors that affe$t the perfor+an$e of the network? a. Number of -sers b. ype of transmission medium

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c. /ardware d. Software 1,. Na+e the fa$tors that affe$t the reia'iity of the network?

a. &re*uency of failure b. )ecovery time of a network after a failure 11. Na+e the fa$tors that affe$t the se$urity of the network? a. -nauthoried Access b. 0iruses 12. What is (roto$o? A protocol is a set of rules that overn all aspects of information communication. 13. What are the key ee+ents of proto$os? he key elements of protocols are a. Syntax It refers to the structure or format of the data, that is the order in which they are presented. b. Semantics It refers to the meanin of each section of bits. c. imin imin refers to two characteristics1 2hen data should be sent and how fast they can be sent. 14. What are the key design issues of a $o+puter Network? a. (onnectivity b. (ost!effective )esource Sharin c. Support for common Services d. 'erformance 15. Define andwidth and Laten$y? Network performance is measured in 3andwidth 4throuhput5 and Latency 4%elay5. 3andwidth of a network is iven by the number of bits that can be transmitted over the network in a certain period of time. Latency corresponds to how lon it t6akes a messae to travel from one end off a network to the other. It is strictly measured in terms of time. 1!. Define Routing? he process of determinin systematically hoe to forward messaes toward the destination nodes based on its address is called routin. 1%. What is a peer-peer pro$ess?

he processes on each machine that communicate at a iven layer are called peer!peer process.


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1). When a swit$h is said to 'e $ongested? It is possible that a switch receives packets faster than the shared link can accommodate and stores in its memory, for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped and in this state is said to conested state. 1*. What is se+anti$ gap? %efinin a useful channel involves both understandin the applications re*uirements and reconiin the limitations of the underlyin technoloy. he ap between what applications expects and what the underlyin technoloy can provide is called semantic ap. 2,. What is Round rip i+e? he duration of time it takes to send a messae from one end of a network to the other and back, is called ). 21. Define the ter+s /ni$asting0 "uti$$asting and road$asting? If the messae is sent from a source to a sinle destination node, it is called -nicastin. If the messae is sent to some subset of other nodes, it is called "ulticastin. If the messae is sent to all the m nodes in the network it is called 3roadcastin. 22. What is "utipeing? "ultiplexin is the set of techni*ues that allows the simultaneous transmission of multiple sinals across a sinle data link. 23. Na+e the $ategories of "utipeing? a. &re*uency %ivision "ultiplexin 4&%"5 b. ime %ivision "ultiplexin 4%"5 i. Synchronous %" ii. ASynchronous %" 7r Statistical %". c. 2ave %ivision "ultiplexin 42%"5 24. What is D"? &%" is an analo techni*ue that can be applied when the bandwidth of a link is reater than the combined bandwidths of the sinals to be transmitted. 25. What is WD"? 2%" is conceptually the same as &%", except that the multiplexin and demultiplexin involve liht sinals transmitted throuh fiber optics channel. 2!. What is D"?

%" is a diital process that can be applied when the data rate capacity of the transmission medium is reater than the data rate re*uired by the sendin and receivin devices.


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2%. What is yn$hronous D"? In S%", the multiplexer allocates exactly the same time slot to each device at all times, whether or not a device has anythin to transmit.

2). List the ayers of  a. 'hysical Layer b. %ata Link Layer c. Network Layer d. ransport Layer e. Session Layer f. 'resentation Layer . Application Layer 2*. Whi$h ayers are network support ayers? a. 'hysical Layer b. %ata link Layer and c. Network Layers 3,. Whi$h ayers are user support ayers? a. Session Layer b. 'resentation Layer and c. Application Layer 31. Whi$h ayer inks the network support ayers and user support ayers? he ransport layer links the network support layers and user support layers. 32. What are the $on$erns of the (hysi$a Layer? 'hysical layer coordinates the functions re*uired to transmit a bit stream over a physical medium. a. 'hysical characteristics of interfaces and media b. )epresentation of bits c. %ata rate d. Synchroniation of bits e. Line confiuration f. 'hysical topoloy . ransmission mode 33. What are the responsi'iities of Data Link Layer? he %ata Link Layer transforms the physical layer, a raw transmission facility, to a reliable link and is responsible for node!node delivery. a. &ramin b. 'hysical Addressin c. &low (ontrol d. $rror (ontrol e. Access (ontrol


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34. What are the responsi'iities of Network Layer? he Network Layer is responsible for the source!to!destination delivery of packet possibly across multiple networks 4links5. a. Loical Addressin b. )outin 35. What are the responsi'iities of ransport Layer? he ransport Layer is responsible for source!to!destination delivery of the entire messae. a. Service!point Addressin b. Sementation and reassembly c. (onnection (ontrol d. &low (ontrol e. $rror (ontrol 3!. What are the responsi'iities of ession Layer? he Session layer is the network dialo (ontroller. It establishes, maintains and synchronies the interaction between the communicatin systems. a. %ialo control b. Synchroniation 3%. What are the responsi'iities of (resentation Layer? he 'resentation layer is concerned with the syntax and semantics of the information exchaned between two systems. a. ranslation b. $ncryption c. (ompression 3). What are the responsi'iities of #ppi$ation Layer? he Application Layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as e!mail, shared database manaement and other types of distributed information services. a. Network virtual erminal b. &ile transfer, access and "anaement 4&A"5 c. "ail services d. %irectory Services 3*. What are the two $asses of hardware 'uiding 'o$ks? Nodes and Links. 4,. What are the different ink types used to 'uid a $o+puter network? a. (ables b. Leased Lines c. Last!"ile Links d. 2ireless Links


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41. What are the $ategories of rans+ission +edia? a. Guided "edia i. wisted ! 'air cable 8. Shielded ' 9. -nshielded ' ii. (oaxial (able iii. &iber!optic cable b. -nuided "edia i. errestrial microwave ii. Satellite (ommunication 42. What are the types of errors? a. Sinle!3it error In a sinle!bit error, only one bit in the data unit has chaned b. 3urst $rror A 3urst error means that two or more bits in the data have chaned. 43. What is 6rror Dete$tion? What are its +ethods? %ata can be corrupted durin transmission. &or reliable communication errors must be deducted and (orrected. $rror %etection uses the concept of redundancy, which means addin extra bits for detectin errors at the destination. he common $rror %etection methods are a. 0ertical )edundancy (heck 40)(5 b. Lonitudinal )edundancy (heck 40)(5 c. (yclic )edundancy (heck 40)(5 d. (hecksum 44. What is Redundan$y? he concept of includin extra information in the transmission solely for the purpose of comparison. his techni*ue is called redundancy. 45. What is 7R8? It is the most common and least expensive mechanism for $rror %etection. In 0)(, a parity bit is added to every data unit so that the total number of 8s becomes even for even parity. It can detect all sinle!bit errors. It can detect burst errors only if the total number of errors in each data unit is odd. 4!. What is LR8? In L)(, a block of bits is divided into rows and a redundant row of bits is added to the whole block. It can detect burst errors. If two bits in one data unit are damaed and bits in exactly the same positions in another data unit are also damaed, the L)( checker will not detect an error. In L)( a redundant data unit follows n data units. 4%. What is 8R8? ()(, is the most powerful of the redundancy checkin techni*ues, is based on binary division.


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4). What is 8he$ksu+? (hecksum is used by the hiher layer protocols 4('#I'5 for error detection 4*. List the steps in&o&ed in $reating the $he$ksu+. a. %ivide the data into sections b. Add the sections toether usin 8+s complement arithmetic c. ake the complement of the final sum, this is the checksum. 5,. What are the Data ink proto$os? %ata link protocols are sets of specifications used to implement the data link layer. he cateories of %ata Link protocols are 8. Asynchronous 'rotocols 9. Synchronous 'rotocols a. (haracter 7riented 'rotocols b. 3it 7riented protocols 51. 8o+pare 6rror Dete$tion and 6rror 8orre$tion9 he correction of errors is more difficult than the detection. In error detection, checks only any error has occurred. In error correction, the exact number of bits that are corrupted and location in the messae are known. he number of the errors and the sie of the messae are important factors. 52. What is orward 6rror 8orre$tion? &orward error correction is the process in which the receiver tries to uess the messae by usin redundant bits. 53. Define Retrans+ission? )etransmission is a techni*ue in which the receiver detects the occurrence of an error and asks the sender to resend the messae. )esendin is repeated until a messae arrives that the receiver believes is error!freed. 54. What are Data Words? In block codin, we divide our messae into blocks, each of k bits, called datawords. he block codin process is one!to!one. he same dataword is always encoded as the same codeword. 55. What are 8ode Words? :r: redundant bits are added to each block to make the lenth n ; k < r. he resultin n! bit blocks are called codewords. 9n ! 9k codewords that are not used. hese codewords are invalid or illeal. 5!. What is a Linear o$k 8ode?

A linear block code is a code in which the exclusive 7) 4addition modulo!95 of two valid codewords creates another valid codeword.


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5%. What are 8y$i$ 8odes? (yclic codes are special linear block codes with one extra property. In a cyclic code, if a codeword is cyclically shifted 4rotated5, the result is another codeword.

5). Define 6n$oder? A device or proram that uses predefined alorithms to encode, or compress audio or video data for storae or transmission use. A circuit that is used to convert between diital video and analo video. 5*. Define De$oder? A device or proram that translates encoded data into its oriinal format 4e.. it decodes the data5. he term is often used in reference to "'$G!9 video and sound data, which must be decoded before it is output. !,. What is ra+ing? &ramin in the data link layer separates a messae from one source to a destination, or from other messaes to other destinations, by addin a sender address and a destination address. he destination address defines where the packet has to o and the sender address helps the recipient acknowlede the receipt. !1. What is ied i:e ra+ing? In fixed!sie framin, there is no need for definin the boundaries of the frames. he sie itself can be used as a delimiter. !2. Define 8hara$ter tuffing? In byte stuffin 4or character stuffin5, a special byte is added to the data section of the frame when there is a character with the same pattern as the fla. he data section is stuffed with an extra byte. his byte is usually called the escape character 4$S(5, which has a predefined bit pattern. 2henever the receiver encounters the $S( character, it removes it from the data section and treats the next character as data, not a delimitin fla. !3. What is it tuffing? 3it stuffin is the process of addin one extra = whenever five consecutive Is follow a = in the data, so that the receiver does not mistake the pattern =88888= for a fla. !4. What is ow 8ontro? &low control refers to a set of procedures used to restrict the amount of data that the sender can send before waitin for acknowledment. !5. What is 6rror 8ontro ?

$rror control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaed in transmission and coordinates the


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retransmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and retransmission. !!. What #uto+ati$ Repeat Re;uest <#R=>?

$rror control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaed in transmission and coordinates the retransmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and retransmission. $rror control in the data link layer is often implemented simply1 Any time an error is detected in an exchane, specified frames are retransmitted. his process is called automatic repeat re*uest 4A)>5. !%. What is top-and-Wait (roto$o? In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from the receiver 4okay to o ahead5, and then sends the next frame. !). What is top-and-Wait #uto+ati$ Repeat Re;uest? $rror correction in Stop!and!2ait A)> is done by keepin a copy of the sent frame and retransmittin of the frame when the timer expires. !*. What is usage of e;uen$e Nu+'er in Reai'e rans+ission? he protocol specifies that frames need to be numbered. his is done by usin se*uence numbers. A field is added to the data frame to hold the se*uence number of that frame. Since we want to minimie the frame sie, the smallest rane that provides unambiuous communication. he se*uence numbers can wrap around. %,. What is (ipeining ? In networkin and in other areas, a task is often beun before the previous task has ended. his is known as pipelinin. %1. What is iding Window? he slidin window is an abstract concept that defines the rane of se*uence numbers that is the concern of the sender and receiver. In other words, he sender and receiver need to deal with only part of the possible se*uence numbers. %2. What is (iggy a$king? A techni*ue called piybackin is used to improve the efficiency of the bidirectional protocols. 2hen a frame is carryin data from A to 3, it can also carry control information about arrived 4or lost5 frames from 3? when a frame is carryin data from 3 to A, it can also carry control information about the arrived 4or lost5 frames from A. %3. What are the two types of trans+ission te$hnoogy a&aia'e? 4i5 3roadcast and 4ii5 point!to!point %4. What is su'net?


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A eneric term for section of a lare networks usually separated by a bride or router. %5. Differen$e 'etween the $o++uni$ation and trans+ission. ransmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc. (ommunication means the meanin full exchane of information between two communication media. %!. What are the possi'e ways of data e$hange? 4i5 Simplex 4ii5 /alf!duplex 4iii5 &ull!duplex. %%. What is #(?

Series of interface points that allow other computers to communicate with the other layers of network protocol stack. %). What do you +eant 'y tripe @ in Networks? he function of 'A% 4'acket Assembler %isassembler5 is described in a document known as @.. he standard protocol has been defined between the terminal and the 'A%, called @.9B? another standard protocol exists between hte 'A% and the network, called @.9C. oether, these three recommendations are often called :triple @:. %*. What is fra+e reay0 in whi$h ayer it $o+es? &rame relay is a packet switchin technoloy. It will operate in the data link layer. ),. What is ter+ina e+uation0 in whi$h ayer it $o+es? elnet is also called as terminal emulation. It belons to application layer. )1. What is ea$oning? he process that allows a network to self!repair networks problems. he stations on the network notify the other stations on the rin when they are not receivin the transmissions. 3eaconin is used in oken rin and &%%I networks. )2. What is redire$tor? )edirector is software that intercepts file or prints I#7 re*uests and translates them into network re*uests. his comes under presentation layer. )3. What is N6 and N66/? N$3I7S is a prorammin interface that allows I#7 re*uests to be sent to and received from a remote computer and it hides the networkin hardware from applications. N$3$-I is Net3I7S extended user interface. A transport protocol desined by microsoft and I3" for the use on small subnets.


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)4. What is R#D? A method for providin fault tolerance by usin multiple hard disk drives. )5. What is passi&e topoogy? 2hen the computers on the network simply listen and receive the sinal, they are referred to as passive because they don+t amplify the sinal in any way. $xample for passive topoloy !linear bus. )!. What is router? /ybrid devices that combine the features of both brides and routers. )%. What is $adding?

A layer of a lass surroundin the center fiber of lass inside a fiber!optic cable. )). What is point-to-point proto$o? A communications protocol used to connect computers to remote networkin services includin Internet service providers. )*. Aow Bateway is different fro+ Routers? A ateway operates at the upper levels of the 7SI model and translates information between two completely different network architectures or data formats. *,. What is attenuation? he deeneration of a sinal over distance on a network cable is called attenuation. *1. What is "#8 address? he address for a device as it is identified at the "edia Access (ontrol 4"A(5 layer in the network architecture. "A( address is usually stored in )7" on the network adapter card and is uni*ue. *2. Differen$e 'etween 'it rate and 'aud rate. 3it rate is the number of bits transmitted durin one second whereas baud rate refers to the number of sinal units per second that are re*uired to represent those bits. baud rate ; 4bit rate # N5 where N is no!of!bits represented by each sinal shift. *3. What is andwidth? $very line has an upper limit and a lower limit on the fre*uency of sinals it can carry. his limited rane is called the bandwidth. *4. What are the types of rans+ission +edia?


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Sinals are usually transmitted over some transmission media that are broadly classified in to two cateories. a.5 Buided "edia1 hese are those that provide a conduit from one device to another that include twisted!pair, coaxial cable and fiber!optic cable. A sinal travelin alon any of these media is directed and is contained by the physical limits of the medium. wisted!pair and coaxial cable use metallic that accept and transport sinals in the form of electrical current. 7ptical fiber is a lass or plastic cable that accepts and transports sinals in the form of liht. b.5 /nguided "edia1 his is the wireless media that transport electromanetic waves without usin a physical conductor. Sinals are broadcast either throuh air. his is done throuh radio communication, satellite communication and cellular telephony. *5. What is (roCe$t ),2? It is a proDect started by I$$$ to set standards to enable intercommunication between e*uipment from a variety of manufacturers. It is a way for specifyin functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of maDor LAN protocols. It consists of the followin1 8. B=9.8 is an internetworkin standard for compatibility of different LANs and "ANs across protocols. 9. B=9.9 Loical link control 4LL(5 is the upper sublayer of the data link layer which is non!architecture!specific, that is remains the same for all I$$$!defined LANs. . "edia access control 4"A(5 is the lower sublayer of the data link layer that contains some distinct modules each carryin proprietary information specific to the LAN product bein used. he modules are $thernet LAN 4B=9.5, oken rin LAN 4B=9.E5, oken bus LAN 4B=9.65. E. B=9.F is distributed *ueue dual bus 4%>%35 desined to be used in "ANs. *!. What is (roto$o Data /nit? he data unit in the LL( level is called the protocol data unit 4'%-5. he '%- contains of four fields a destination service access point 4%SA'5, a source service access point 4SSA'5, a control field and an information field. %SA', SSA' are addresses used by the LL( to identify the protocol stacks on the receivin and sendin machines that are eneratin and usin the data. he control field specifies whether the '%- frame is a information frame 4I ! frame5 or a supervisory frame 4S ! frame5 or a unnumbered frame 4- ! frame5. *%. What are the different type of networking  internetworking de&i$es?

1. Repeater1 Also called a reenerator, it is an electronic device that operates only

2.

at physical layer. It receives the sinal in the network before it becomes weak, reenerates the oriinal bit pattern and puts the refreshed copy back in to the link. ridges1 hese operate both in the physical and data link layers of LANs of same type. hey divide a larer network in to smaller sements. hey contain loic that allow them to keep the traffic for each sement separate and thus are repeaters that relay a frame only the side of the sement containin the intended recipent and control conestion.


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3. Routers1 hey relay packets amon multiple interconnected networks 4i.e. LANs

4.

of different type5. hey operate in the physical, data link and network layers. hey contain software that enable them to determine which of the several possible paths is the best for a particular transmission. Bateways1 hey relay packets amon networks that have different protocols 4e.. between a LAN and a 2AN5. hey accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwardin it. hey operate in all seven layers of the 7SI model.

*). What is 8"(? I("' is Internet (ontrol "essae 'rotocol, a network layer protocol of the ('#I' suite used by hosts and ateways to send notification of dataram problems back to the sender. It uses the echo test # reply to test whether a destination is reachable and respondin. It also handles both control and error messaes. **. What are the data units at different ayers of the 8(  ( proto$o suite? he data unit created at the application layer is called a messae, at the transport layer the data unit created is called either a sement or an user dataram, at the network layer the data unit created is called the dataram, at the data link layer the dataram is encapsulated in to a frame and finally transmitted as sinals alon the transmission media. 1,,. What is differen$e 'etween #R( and R#R(? he address resolution protocol 4A)'5 is used to associate the 9 bit I' address with the EB bit physical address, used by a host or a router to find the physical address of another host on its network by sendin a A)' *uery packet that includes the I' address of the receiver. he reverse address resolution protocol 4)A)'5 allows a host to discover its Internet address when it knows only its physical address. 1,1. What is the +ini+u+ and +ai+u+ ength of the header in the 8( seg+ent and ( datagra+? he header should have a minimum lenth of 9= bytes and can have a maximum lenth of F= bytes.

1,2. What is the range of addresses in the $asses of internet addresses? (lass (lass (lass (lass (lass

A 3 ( % $

! =.=.=.= ! 89.966.966.966 ! 89B.=.=.= ! 8C8.966.966.966 ! 8C9.=.=.= ! 99.966.966.966 ! 99E.=.=.= ! 9C.966.966.966 ! 9E=.=.=.= ! 9E.966.966.966

1,3. What is the differen$e 'etween ( and ( appi$ation ayer proto$os? he rivial &ile ransfer 'rotocol 4&'5 allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by -%'.


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he &ile ransfer 'rotocol 4&'5 is the standard mechanism provided by (' # I' for copyin a file from one host to another. It uses the services offer by (' and so is reliable and secure. It establishes two connections 4virtual circuits5 between the hosts, one for data transfer and another for control information.

1,4. What are +aCor types of networks and epain?

1. er&er-'ased network1 provide centralied control of network resources and rely on server computers to provide security and network administration

2. (eer-to-peer network1 computers can act as both servers sharin resources and as clients usin the resources. 1,5. What are the i+portant topoogies for networks?

1. / topoogy1 In this each computer is directly connected to primary network

2.

cable in a sinle line. Advantaes1 Inexpensive, easy to install, simple to understand, easy to extend. #R topoogy1 In this all computers are connected usin a central hub.

3.

Advantaes1 (an be inexpensive, easy to install and reconfiure and easy to trouble shoot physical problems. RNB topoogy1 In this all computers are connected in loop. Advantaes1 All computers have e*ual access to network media, installation can be simple, and sinal does not derade as much as in other topoloies because each computer reenerates it.

1,!. What is +esh network? A network in which there are multiple network links between computers to provide multiple paths for data to travel. 1,%. What is differen$e 'etween 'ase'and and 'road'and trans+ission? In a baseband transmission, the entire bandwidth of the cable is consumed by a sinle sinal. In broadband transmission, sinals are sent on multiple fre*uencies, allowin multiple sinals to be sent simultaneously. 1,). 6pain 5-4-3 rue? In a $thernet network, between any two points on the network ,there can be no more than five network sements or four repeaters, and of those five sements only three of sements can be populated. 1,*. What "#/? In token )in , hub is called "ultistation Access -nit4"A-5. 11,. What is the differen$e 'etween routa'e and non- routa'e proto$os? )outable protocols can work with a router and can be used to build lare networks. Non! )outable protocols are desined to work on small, local networks and cannot be used with a router. 111. Why shoud you $are a'out the  Referen$e "ode?


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It provides a framework for discussin network operations and desin. 112. What is ogi$a ink $ontro? 7ne of two sublayers of the data link layer of 7SI reference model, as defined by the I$$$ B=9 standard. his sublayer is responsible for maintainin the link between computers when they are sendin data across the physical network connection. 113. What is &irtua $hanne? 0irtual channel is normally a connection from one source to one destination, althouh multicast connections are also permitted. he other name for virtual channel is virtual circuit. 114. What is &irtua path?

Alon path frominto a iven to path. a iven destination, a roup of virtual circuitsany cantransmission be rouped toether whatsource is called 115. What is pa$ket fiter? 'acket filter is a standard router e*uipped with some extra functionality. he extra functionality allows every incomin or outoin packet to be inspected. 'ackets meetin some criterion are forwarded normally. hose that fail the test are dropped. 11!. What is traffi$ shaping? 7ne of the main causes of conestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, conestion would be less common. Another open loop method to help manae conestion is forcin the packet to be transmitted at a more predictable rate. his is called traffic shapin. 11%. What is +uti$ast routing? Sendin a messae to a roup is called multicastin, and its routin alorithm is called multicast routin. 11). What is region? 2hen hierarchical routin is used, the routers are divided into what we will call reions, with each router knowin all the details about how to route packets to destinations within its own reion, but knowin nothin about the internal structure of other reions. 11*. What is siy window syndro+e? It is a problem that can ruin (' performance. his problem occurs when data are passed to the sendin (' entity in lare blocks, but an interactive application on the receivin side reads 8 byte at a time. 12,. What are Digra+s and rigra+s?


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he most common two letter combinations are called as dirams. e.. th, in, er, re and an. he most common three letter combinations are called as trirams. e.. the, in, and, and ion. 121. 6pand D6#. I%$A stands for International %ata $ncryption Alorithm. 122. What is wide-+outh frog? 2ide!mouth fro is the simplest known key distribution center 4H%(5 authentication protocol. 123. What is "ai Bateway? It is a system that performs a protocol translation between different electronic mail delivery protocols. 124. What is B( <nterior Bateway (roto$o>? It is any routin protocol used within an autonomous system. 125. What is 6B( <6terior Bateway (roto$o>? It is the protocol the routers in neihborin autonomous systems use to identify the set of networks that can be reached within or via each autonomous system. 12!. What is autono+ous syste+? It is a collection of routers under the control of a sinle administrative authority and that uses a common Interior Gateway 'rotocol. 12%. What is B( <order Bateway (roto$o>? It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. 3G' enables this information to be shared with the autonomous system. his is newer than $G' 4$xterior Gateway 'rotocol5. 12). What is Bateway-to-Bateway proto$o? It is a protocol formerly used to exchane routin information between Internet core routers. 12*. What is N7 ? It is a set of rules definin a very simple virtual terminal interaction. he N0 is used in the start of a elnet session. 13,. What is a "uti-ho+ed Aost? It is a host that has a multiple network interfaces and that re*uires multiple I' addresses is called as a "ulti!homed /ost.


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131. What is Eer'eros? It is an authentication service developed at the "assachusetts Institute of echnoloy. Herberos uses encryption to prevent intruders from discoverin passwords and ainin unauthoried access to files. 132. What is (? It is an Internet routin protocol that scales well, can route traffic alon multiple paths, and uses knowlede of an Internet+s topoloy to make accurate routin decisions. 133. What is (roy #R(? It is usin a router to answer A)' re*uests. his will be done when the oriinatin host believes that a destination is local, when in fact is lies beyond router.

134. What is L( <eria Line nterfa$e (roto$o>? It is a very simple protocol used for transmission of I' datarams across a serial line. 135. What is R( ? It is a simple protocol used to exchane information between the routers. 13!. What is sour$e route? It is a se*uence of I' addresses identifyin the route a dataram must follow. A source route may optionally be included in an I' dataram header.

When were OSI model developed and why its standard called 802.XX and so on? OSI model was developed in February1980 that why these also known as 802.XX Standard !oti"e 80 means ##$ 1980% 2means ##$ February&

What is Full form of !S? '"tive (ire"tory Stru"ture

"ow will you re#ister and activate windows? I) you have not a"tivated windows X*% you "an do so at any time by "li"kin+ the windows '"tivation i"on in the system tray to initiate a"tivation. On"e you have a"tivated windows X*% this i"on disappears )rom the system tray. For re+istration Start ##$ ,un ##$ re+wi- r

Where do we use cross and standard ca$le?


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/omputer to "omputer ##$ "ross Swit"hhub to swit"hhub ##$"ross /omputer to swit"hhub ##$standard

"ow many pins do serial ports have? In "omputer its known as "om port and "ould be available in 9pin or 2 pin. On router it have 0 pins.

"ow will chec% ip address on &8? Start ##$ ,un ##$ "ommand ##$ winip")+

"ow will you ma%e partition after installin# windows? 3y "omputer ##$ ri+ht "li"k ##$ mana+e ##$ disk mana+ement ##$ sele"t )ree spa"e ##$ ri+ht "li"k ##$ !ew partition

What is I'? Its a uni4ue 52 bits so)tware address o) a node in a network.

What is private I'? 6hree ran+es o) I* addresses have been reserved )or private address and they are not valid )or use on the Internet. I) you want to a""ess internet with these address you must have to use pro7y server or !'6 server on normal "ases the role o) pro7y server is played by your IS*.&.I) you do de"ide to implement a private I* address ran+e% you "an use I* addresses )rom any o) the )ollowin+ "lasses /lass ' 10.0.0.0 10.2.2.2 /lass  1:2.1.0.0 1:2.51.2.2 /lass / 192.18.0.0 192.18.2.2

What is pu$lic I' address? ' publi" I* address is an address leased )rom an IS* that allows or enables dire"t Internet "ommuni"ation.

What(s the $enefit of su$nettin#?


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,edu"e the si-e o) the routin+ tables. ,edu"e network tra))i". road"ast tra))i" "an be isolated within a sin+le lo+i"al network. *rovide a way to se"ure network tra))i" by isolatin+ it )rom the rest o) the network.

What are the differences $etween static ip addressin# and dynamic ip addressin#? ;ith stati" I* addressin+% a "omputer or other devi"e& is "on)i+ured to always use the same I* address. ;ith dynami" addressin+% the I* address "an "han+e periodi"ally and is mana+ed by a "entrali-ed network servi"e

What is 'I'? 'utomati" private I* addressin+ '*I*'& is a )eature mainly )ound in 3i"roso)t operatin+ systems. '*I*' enables "lients to still "ommuni"ate with other "omputers on the same network se+ment until an I* address "an be obtained )rom a (peer "onne"tion. In

*eer ?to>*eer networkin+ model

every peer are

e4ually privile+ed and they distribute the work load amon+ them. /lient ?server model o) "omputin+ where task is distributed between providers o) servi"e "alled servers and servi"e re4uester "alled "lients. )*+ What is a protocol? '& *roto"ol is a set o) rules )or data "ommuni"ation and trans)er. It de)ines what is "ommuni"ated% how it is "ommuni"ated% when it "an be "ommuni"ated. @ey elements o) proto"ol are semanti"s% synta7 and timin+. )*+ ,ell a$out ,-'I' protocol? '& 6ransmission /ontrol *roto"olInternet *roto"ol 6/*I*& is the basi" "ommuni"ation proto"ol. It also used in Intranet and e7tranet. 6/*I* uses the "lientserver model o) "ommuni"ation in whi"h a "omputer user re4uest and heshe will be provided a servi"e.


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)*+ What is switchin#? '& Swit"hin+ in data "ommuni"ation is o) 5 types /ir"uit swit"hin+% *a"ket swit"hin+ and 3assa+e swit"hin+ )*+ !ifference $etween nalo# and di#ital si#nals? '& 'nalo+ si+nals have unlimited number o) values where as di+ital si+nal has limited number o) values. )*+ In which form !ata is transmitted over a medium? '& (ata is transmitted over a medium in the )orm o) ele"troma+neti" si+nals. )*+ What is /andwidth? '& andwidth is the ran+e di))eren"e between hi+hest )re4uen"y and lowest )re4uen"y& o) )re4uen"y that a medium "an pass. )*+ ist the factors on which !ata transmission depends? '& It depends on andwidth% 4uality o) si+nals and levels o) si+nals. )*+ What is 1I'? '& ,I* stands )or routin+ In)ormation *roto"ol. ,I* is used )or e7"han+in+ in)ormation between two routers. )*+ ,ell a$out 'I3 utility? '& *I!A stands )or *a"ket Internet Aopher. *I!A is used to ensure "onne"tivity between two "omputers. I/3* Internet /ontrol 3essa+in+ proto"ol& proto"ol works behind this utility. )*+ !ifference $etween "u$s4 Switch and 1outers? '&
,outer is a devi"e that )orwards data pa"kets alon+ the network. )*+ ,ell a$out nonymous F,' and its uses? '& ;hen you want to "onne"t to host without any lo+ins then 'nonymous F6* provides a""ess in a +uest or anonymous )orm. 'nonymous F6* has very stri"t "ontrol over a""ess areas o) anonymous user.

s

What is a $o+puter Network?


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A network is any collection of independent computers that communicate with one another over a shared network medium. A computer network is a collection of

two or more connected computers. When these computers are joined in a network, people can share files and peripherals such as modems, printers, tape backup drives, or CD-RO drives. When networks at multiple locations are connected usin! services available from phone companies, people can send e-mail, share links to the !lobal "nternet, or conduct video conferences in real time with other remote users. When a network becomes open sourced it can be mana!ed properl# with online collaboration software. As companies rel# on applications like electronic mail and database mana!ement for core business operations, computer networkin! becomes increasin!l# more important. Every network includes:

•

•

•

At least two computers Server or Client workstation. Networking Interface Card's (NIC) A connection medium, usually a wire or cale,

alt!oug! wireless communication etween networked computers and perip!erals is also possile. Network "perating system software, suc! as #icrosoft •

$indows N% or &, Novell Net$are, ni and *inu.

ypes of Networks9 L#Ns A network is an# collection of independent computers that communicate with one another over a shared network medium. LANs are networks usually confined to a geographic area, such as a sin!le buildin! or a colle!e campus. $A%s can be small,

linkin! as few as three computers, but often link hundreds of computers used b# thousands of people. &he development of standard networkin! protocols and media has resulted in worldwide proliferation of $A%s throu!hout business and educational or!ani'ations.

W#Ns


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Wide area networking combines multiple LANs that are geographically separate. &his

is accomplished b# connectin! the different $A%s usin! services such as dedicated leased phone lines, dial-up phone lines (both s#nchronous and as#nchronous), satellite links, and data packet carrier services. Wide area networkin! can be as simple as a modem and remote access server for emplo#ees to dial into, or it can be as comple* as hundreds of branch offices !loball# linked usin! special routin! protocols and filters to minimi'e the e*pense of sendin! data sent over vast distances.

nternet The Internet is a system of linked networks that are worldwide in scope and facilitate data communication services such as remote lo!in, file

transfer, electronic mail, the World Wide Web and news!roups. With the meteoric rise in demand for connectivit#, the "nternet has become a communications hi!hwa# for millions of users. &he "nternet was initiall# restricted to militar# and academic institutions, but now it is a full-fled!ed conduit for an# and all forms of information and commerce. "nternet websites now provide personal, educational, political and economic resources to ever# corner of the planet.

ntranet With the advancements made in browser-based software for the "nternet, man# private or!ani'ations are implementin! intranets. An intranet is a private network utiliing Internet!type tools, but available onl# within that or!ani'ation. +or lar!e

or!ani'ations, an intranet provides an eas# access mode to corporate information for emplo#ees.

"#Ns <"etropoitan area Networks> &he refers to a network of computers with in a Cit#.

7(N <7irtua (ri&ate Network>


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% uses a techniue known as tunnelin! to transfer data securel# on the "nternet to a remote access server on #our workplace network. /sin! a % helps #ou save mone# b# usin! the public "nternet instead of makin! lon!0distance phone calls to connect securel# with #our private network. &here are two wa#s to create a % connection, b# dialin! an "nternet service provider ("1), or connectin! directl# to "nternet.

Categories of Network: Network $an


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'e di&ided in to two +ain $ategories9 •

Peer-to-peer.

•

Server – based.

"n peer-to-peer networkin! there are no dedicated servers or hierarch# amon! the computers. All of the computers are eual and therefore known as peers. %ormall# each computer serves as Client21erver and there is no one assi!ned to be an administrator responsible for the entire network. eer-to-peer networks are !ood choices for needs of small or!ani'ations where the users are allocated in the same !eneral area, securit# is not an issue and the or!ani'ation and the network will have limited !rowth within the foreseeable future. &he term Client2server refers to the concept of sharin! the work involved in processin! data between the client computer and the most powerful server computer.

he $ientser&er network is the +ost effi$ient way to pro&ide9 •

Databases and management of applications such as Spreadsheets, ccounting, !ommunications and Document management.

•

"et#or$ management.

•

!entrali%ed file storage.

&he client2server model is basicall# an implementation of distributed or cooperative processin!. At the heart of the model is the concept of splittin! application functions between a client and a server processor. &he division of labor between the different processors enables the application desi!ner to place an application function on the processor that is most appropriate for that function. &his lets the software desi!ner optimi'e the use of processors--providin! the !reatest possible return on investment for the hardware. Client2server application desi!n also lets the application provider mask the actual


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location of application function. &he user often does not know where a specific operation is e*ecutin!. &he entire function ma# e*ecute in either the C or server, or the function ma# be split between them. &his maskin! of application function locations enables s#stem implementers to up!rade portions of a s#stem over time with a minimum disruption of application operations, while protectin! the investment in e*istin! hardware and software.

The OSI Model: "pen #ystem Interconnection $"#I% reference model has become

an "nternational standard and serves as a !uide for networkin!. &his model is the best known and most widel# used !uide to describe networkin! environments. endors desi!n network products based on the specifications of the O1" model. "t provides a description of how network hardware and software work to!ether in a la#ered fashion to make communications possible. "t also helps with trouble shootin! b# providin! a frame of reference that describes how components are supposed to function. &here are seven to !et familiar with and these are the ph#sical la#er, data link la#er, network la#er, transport la#er, session la#er, presentation la#er, and the application la#er. •

Physical Layer, is &ust that the ph'sical parts of the net#or$ such as #ires, cables, and there media along #ith the length. lso this la'er ta$es note of the electrical signals that transmit data throughout s'stem.

•

Data Link Layer, this la'er is #here #e actuall' assign meaning to the electrical signals in the net#or$. (he la'er also determines the si%e and format of data sent to printers, and other devices. lso )


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don*t #ant to forget that these are also called nodes in the net#or$. nother thing to consider in this la'er is #ill also allo# and define the error detection and correction schemes that insure data #as

•

sent and received. Network Layer, this la'er provides the definition for the connection of t#o dissimilar net#or$s.

•

(ransport +a'er, this la'er allo#s data to be bro$en into smaller pac$ages for data to be distributed and addressed to other nodes #or$stations.

•

Session Layer, this la'er helps out #ith the tas$ to carr' information from one node #or$station to another node #or$station.  session has to be made before #e can transport information to another computer.

•

Presentation Layer, this la'er is responsible to code and decode data sent to the node.

•

Application Layer, this la'er allo#s 'ou to use an application that #ill communicate #ith sa' the operation s'stem of a server.  good eample #ould be using 'our #eb bro#ser to interact #ith the operating s'stem on a server such as /indo#s "(, #hich in turn gets the data 'ou re0uested.


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Network Architectures:

6thernet &thernet is the most popular physical layer LAN technology in use today. Other $A%

t#pes include &oken Rin!, +ast 3thernet, +iber Distributed Data "nterface (+DD"), As#nchronous &ransfer ode (A&) and $ocal&alk. 3thernet connection is popular because it strikes a !ood balance between speed, cost and ease of installation. &hese benefits, combined with wide acceptance in the computer marketplace and the abilit# to support virtuall# all popular network protocols, make 3thernet an ideal networkin! technolo!# for most computer users toda#. &he "nstitute for 3lectrical and 3lectronic 3n!ineers ("333) defines the 3thernet standard as "333 1tandard 456.7. &his standard defines rules for confi!urin! an 3thernet network as well as specif#in! how elements in an 3thernet network interact with one another. 8# adherin! to the "333 standard, network euipment and network protocols can communicate efficientl#.

ast 6thernet


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'or &thernet networks that need higher transmission speeds, the 'ast &thernet standard $I&&& ()*.+u% has been established. &his standard raises the 3thernet speed

limit from 95 e!abits per second (bps) to 955 bps with onl# minimal chan!es to the e*istin! cable structure. &here are three t#pes of +ast 3thernet: 9558A13-&; for use with level < /& cable, 9558A13-+; for use with fiber-optic cable, and 9558A13-&= which utili'es an e*tra two wires for use with level 7 /& cable. &he 9558A13-&; standard has become the most popular due to its close compatibilit# with the 958A13-& 3thernet standard. +or the network mana!er, the incorporation of +ast 3thernet into an e*istin! confi!uration presents a host of decisions. ana!ers must determine the number of users in each site on the network that need the hi!her throu!hput, decide which se!ments of the backbone need to be reconfi!ured specificall# for 9558A13-& and then choose the necessar# hardware to connect the 9558A13-& se!ments with e*istin! 958A13-& se!ments. >i!abit 3thernet is a future technolo!# that promises a mi!ration path be#ond +ast 3thernet so the ne*t !eneration of networks will support even hi!her data transfer speeds.

oken Ring Token Ring is another form of network

confi!uration which differs from 3thernet in that all messa!es are transferred in a unidirectional manner alon! the rin! at all times. Data is transmitted in tokens, which are passed alon! the rin! and viewed b# each device. When a device sees a messa!e addressed to it, that device copies the messa!e and then marks that messa!e as bein! read. As the messa!e makes its wa# alon! the rin!, it eventuall# !ets back to the sender who now notes that the messa!e was received b# the intended device. &he sender can then remove the messa!e and free that token for use b# others. arious C vendors have been proponents of &oken Rin! networks at different times and thus these t#pes of networks have been implemented in man# or!ani'ations.

DD


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FDDI (FiberDistributed Data Interface! is a standard for data transmission on

fiber optic lines in a local area network that can e*tend in ran!e up to 655 km (96= miles). &he +DD" protocol is based on the token rin! protocol. "n addition to bein! lar!e !eo!raphicall#, an +DD" local area network can support thousands of users.

Protocols: "etwork protocols are standards that allow computers to communicate. A

protocol defines how computers identif# one another on a network, the form that the data should take in transit, and how this information is processed once it reaches its final destination. rotocols also define procedures for handlin! lost or dama!ed transmissions or ?packets.? &C2" (for /%";, Windows %&, Windows @< and other platforms), "; (for %ovell %etWare), D3Cnet (for networkin! Di!ital 3uipment Corp. computers), Apple&alk (for acintosh computers), and %et8"O12%et83/" (for $A% ana!er and Windows %& networks) are the main t#pes of network protocols in use toda#. Althou!h each network protocol is different, the# all share the same ph#sical cablin!. &his common method of accessin! the ph#sical network allows multiple protocols to peacefull# coe*ist over the network media, and allows the builder of a network to use common hardware for a variet# of protocols. &his concept is known as ?protocol independence,? 1ome "mportant rotocols and their job:

Protocol

Acrony

Its Jo

m Point-(o-Point

(!P)P

(he bac$bone protocol of the internet. Popular also for intranets using the internet

(ransmission !ontrol (!P)P Protocolinternet Protocol

(he bac$bone protocol of the internet. Popular


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also for intranets using the internet )nternet#or$ Pac$age )PSP

(his is a standard

changeSe0uenced

protocol for "ovell

Pac$et change

"et#or$ perating S'stem

"et5)S tended

"et56)

6ser )nterface

(his is a 7icrosoft protocol that doesn*t support routing to other net#or$s

8ile (ransfer Protocol

8(P

6sed to send and receive files from a remote host

9'per (et (ransfer

9((P

Protocol

6sed for the #eb to send documents that are encoded in 9(7+.

"et#or$ 8ile Services "8S

llo#s net#or$ nodes or #or$stations to access files and drives as if the' #ere their o#n.

Simple 7ail (ransfer Protocol

S7(P

6sed to send mail over a net#or$

(elnet

6sed to connect to a host and emulate a terminal that the


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remote server can recogni%e

Introduction to TCP/IP Networks: T-I-!based networks play an increasingly important role in computer networks. erhaps one reason for their appeal is that the# are based on an open

specification that is not controlled b# an# vendor.

What s 8((? T#$ stands for Transmission #ontrol $rotocol and I$ stands for Internet $rotocol. &he term &C2" is not limited just to these two protocols, however.

+reuentl#, the term &C2" is used to refer to a !roup of protocols related to the &C and " protocols such as the /ser Data!ram rotocol (/D), +ile &ransfer rotocol (+&), &erminal 3mulation rotocol (&3$%3&), and so on.

he rigins of 8(( "n the late 9@5s, DARA (the Defense Advanced Research roject A!enc#), in the /nited 1tates, noticed that there was a rapid proliferation of computers in militar# communications. Computers, because the# can be easil# pro!rammed, provide fle*ibilit# in achievin! network functions that is not available with other t#pes of communications euipment. &he computers then used in militar# communications were manufactured b# different vendors and were desi!ned to interoperate with computers from that vendor onl#. endors used proprietar# protocols in their communications euipment. &he militar# had a multi vendor network but no common protocol to support the hetero!eneous euipment from different vendors

Net work Cables and Stuff: "n the network #ou will commonl# find three t#pes of cables used these are the, coa*ial cable, fiber optic and twisted pair.


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hi$k 8oaia 8a'e &his t#pe cable is usuall# #ellow in color and used in what is called thicknets, and has two conductors. &his coa* can be used in <55-meter len!ths. &he cable itself is made up of a solid center wire with a braided metal shield and plastic sheathin! protectin! the rest of the wire.

hin 8oaia 8a'e As with the thick coa*ial cable is used in thicknets the thin version is used in thinnets. &his t#pe cable is also used called or referred to as R>-<4. &he cable is reall# just a cheaper version of the thick cable.

i'er pti$ 8a'e As we all know fiber optics are prett# darn cool and not cheap. &his cable is smaller and can carr# a vast amount of information fast and over lon! distances.

wisted (air 8a'es &hese come in two flavors of unshielded and shielded.

hieded wisted (air <(> "s more common in hi!hspeed networks. &he bi!!est difference #ou will see in the /& and 1& is that the 1& useBs metallic shield wrappin! to protect the wire from interference.


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-1omethin! else to note about these cables is that the# are defined in numbers also. &he bi!!er the number the better the protection from interference. ost networks should !o with no less than a CA& 7 and CA& < is most recommended. -%ow #ou know about cables we need to know about connectors. &his is prett# important and #ou will most likel# need the R-=< connector. &his is the cousin of the phone jack connector and looks real similar with the e*ception that the R-=< is bi!!er. ost commonl# #our connector are in two flavors and this is 8%C (8a#onet %aur Connector) used in thicknets and the R-=< used in smaller networks usin! /&21&.

/nshieded wisted (air &his is the most popular form of cables in the network and the cheapest form that #ou can !o with. &he /& has four pairs of wires and all inside plastic sheathin!. &he bi!!est reason that we call it &wisted air is to protect the wires from interference from themselves. 3ach wire is onl# protected with a thin plastic sheath.

6thernet 8a'ing %ow to familiari'e #ou with more on the 3thernet and itBs cablin! we need to look at the 95Bs. 958ase6, is considered the thin 3thernet, thinnet, and thinwire which uses li!ht coa*ial cable to create a 95 bps network. &he cable se!ments in this network canBt be over 94< meters in len!th. &hese cables connect with the 8%C connector. Also as a note these unused connection must have a terminator, which will be a <5ohm terminator. %&'ase, this is considered a thicknet and is used with coa*ial cable arran!ement

such as the 8%C connector. &he !ood side to the coa*ial cable is the hi!h-speed transfer and cable se!ments can be up to <55 meters between nodes2workstations. ou will t#picall# see the same speed as the 958ase6 but lar!er cable len!ths for more versatilit#. %&'aseT, the E&F stands for twisted as in /& (/nshielded &wisted air) and uses

this for 95bps of transfer. &he down side to this is #ou can onl# have cable len!ths of 955 meters between nodes2workstations. &he !ood side to this network is the# are


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eas# to set up and cheapG &his is wh# the# are so common an ideal for small offices or homes.

%&&'aseT, is considered +ast 3thernet uses 1& (1hielded &wisted air) reachin! data transfer of 955bps. &his s#stem is a little more e*pensive but still remains

popular as the 958ase& and cheaper than most other t#pe networks. &his on of course would be the cheap fast version. %&'aseF, this little !u# has the advanta!e of fiber optics and the + stands for just that.

&his arran!ement is a little more complicated and uses special connectors and %"CBs alon! with hubs to create its network. rett# darn neat and not to cheap on the wallet. An important part of desi!nin! and installin! an 3thernet is selectin! the appropriate 3thernet medium. &here are four major t#pes of media in use toda#: &hickwire for 958A13< networks, thin coa* for 958A136 networks, unshielded twisted pair (/&) for 958A13-& networks and fiber optic for 958A13-+$ or +iber-Optic "nterRepeater $ink (+O"R$) networks. &his wide variet# of media reflects the evolution of 3thernet and also points to the technolo!#Bs fle*ibilit#. &hickwire was one of the first cablin! s#stems used in 3thernet but was e*pensive and difficult to use. &his evolved to thin coa*, which is easier to work with and less e*pensive.

Network Topologies: What is a Network topoogy? A network topolo!# is the !eometric arran!ement of nodes and cable links in a $A%, &here are three topolo!#Bs to think about when #ou !et into networks. &hese are the star, rind, and the bus. )tar, in a star topolo!# each node has a dedicated set of wires connectin! it to a

central network hub. 1ince all traffic passes throu!h the hub, the hub becomes a central point for isolatin! network problems and !atherin! network statistics. Ring, a rin! topolo!# features a lo!icall# closed loop. Data packets travel in a sin!le


34/51



direction around the rin! from one network device to the ne*t. 3ach network device acts as a repeater, meanin! it re!enerates the si!nal

'us, the bus topolo!#, each node (computer, server, peripheral etc.) attaches directl# to a common cable. &his topolo!# most often serves as the backbone for a network. "n

some instances, such as in classrooms or labs, a bus will connect small work!roups

Collisions: 3thernet is a shared media, so there are rules for sendin! packets of data to avoid conflicts and protect data inte!rit#. %odes determine when the network is available for sendin! packets. "t is possible that two nodes at different locations attempt to send data at the same time. When both Cs are transferrin! a packet to the network at the same time, a collision will result. inimi'in! collisions is a crucial element in the desi!n and operation of networks. "ncreased collisions are often the result of too man# users on the network, which results in a lot of contention for network bandwidth. &his can slow the performance of the network from the userBs point of view. 1e!mentin! the network, where a network is divided into different pieces joined to!ether lo!icall# with a brid!e or switch, is one wa# of reducin! an overcrowded network.

thernet Products: &he standards and technolo!# that have just been discussed help define the specific products that network mana!ers use to build 3thernet networks. &he followin! te*t discusses the ke# products needed to build an 3thernet $A%.

rans$ei&ers Transceivers are used to connect nodes to the various 3thernet media. ost

computers and network interface cards contain a built-in 958A13-& or 958A136 transceiver, allowin! them to be connected directl# to 3thernet without reuirin! an e*ternal transceiver. an# 3thernet devices provide an A/" connector to allow the user to connect to an# media t#pe via an e*ternal transceiver. &he A/" connector consists of a 9<-pin D-shell t#pe connector, female on the computer side, male on the


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transceiver side. &hickwire (958A13<) cables also use transceivers to allow connections.

+or +ast 3thernet networks, a new interface called the "" (edia "ndependent "nterface) was developed to offer a fle*ible wa# to support 955 bps connections. &he "" is a popular wa# to connect 9558A13-+; links to copper-based +ast 3thernet devices.

Network Interface Cards: "etwork interface cards,

commonl# referred to as %"Cs, and are used to connect a C to a network. &he %"C provides a ph#sical connection between the networkin! cable and the computerBs internal bus. Different computers have different bus architecturesH C" bus master slots are most commonl# found on =42entium Cs and "1A e*pansion slots are commonl# found on 74 and older Cs. %"Cs come in three basic varieties: 4-bit, 9-bit, and 76-bit. &he lar!er the number of bits that can be transferred to the %"C, the faster the %"C can transfer data to the network cable. an# %"C adapters compl# with lu!-n-la# specifications. On these s#stems, %"Cs are automaticall# confi!ured without user intervention, while on non-lu!-n-la# s#stems, confi!uration is done manuall# throu!h a setup pro!ram and2or D" switches. Cards are available to support almost all networkin! standards, includin! the latest +ast 3thernet environment. +ast 3thernet %"Cs are often 952955 capable, and will automaticall# set to the appropriate speed. +ull duple* networkin! is another option, where a dedicated connection to a switch allows a %"C to operate at twice the speed.


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!ubs/"epeaters: *ubs+repeaters are used to connect to!ether two or more 3thernet se!ments of an#

media t#pe. "n lar!er desi!ns, si!nal ualit# be!ins to deteriorate as se!ments e*ceed their ma*imum len!th. Iubs provide the si!nal amplification reuired to allow a se!ment to be e*tended a !reater distance. A hub takes an# incomin! si!nal and repeats it out all ports. 3thernet hubs are necessar# in star topolo!ies such as 958A13-&. A multi-port twisted pair hub allows several point-to-point se!ments to be joined into one network. One end of the point-to-point link is attached to the hub and the other is attached to the computer. "f the hub is attached to a backbone, then all computers at the end of the twisted pair se!ments can communicate with all the hosts on the backbone. &he number and t#pe of hubs in an# one-collision domain is limited b# the 3thernet rules. &hese repeater rules are discussed in more detail later. "a# Nodes

"a# Distance

Per Se$ment

Per Se$ment

1:5S-( 1:5S2

2 3:

1::m 1<;m

1:5S;

1::

;::m

1:5S-8+

2

2:::m

Network !ype

Adding Speed: While repeaters allow $A%s to e*tend be#ond normal distance limitations, the# still limit the number of nodes that can be supported. 8rid!es and switches, however, allow $A%s to !row si!nificantl# lar!er b# virtue of their abilit# to support full 3thernet se!ments on each port. Additionall#, brid!es and switches selectivel# filter network traffic to onl# those packets needed on each se!ment - this si!nificantl# increases throu!hput on each se!ment and on the overall network. 8# providin! better performance and more fle*ibilit# for network topolo!ies, brid!es and switches will continue to !ain popularit# amon! network mana!ers.


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#ridges: &he function of a brid!e is to connect separate networks to!ether. 'ridges connect different networks t#pes (such as 3thernet and +ast 3thernet) or networks of the same t#pe. 8rid!es map the 3thernet addresses of the nodes residin! on each network se!ment and allow onl# necessar# traffic to pass throu!h the brid!e. When a packet is received b# the brid!e, the brid!e determines the destination and source se!ments. "f the se!ments are the same, the packet is dropped (?filtered?)H if the se!ments are different, then the packet is ?forwarded? to the correct se!ment. Additionall#, brid!es do not forward bad or misali!ned packets. 8rid!es are also called ?store-and-forward? devices because the# look at the whole 3thernet packet before makin! filterin! or forwardin! decisions. +ilterin! packets, and re!eneratin! forwarded packets enable brid!in! technolo!# to split a network into separate collision domains. &his allows for !reater distances and more repeaters to be used in the total network desi!n.

thernet

Switches: ,thernet switches are an e*pansion of the concept in 3thernet brid!in!. $A%

switches can link four, si*, ten or more networks to!ether, and have two basic architectures: cut-throu!h and store-and-forward. "n the past, cut-throu!h switches were faster because the# e*amined the packet destination address onl# before forwardin! it on to its destination se!ment. A store-and-forward switch, on the other hand, accepts and anal#'es the entire packet before forwardin! it to its destination.


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"t takes more time to e*amine the entire packet, but it allows the switch to catch certain packet errors and keep them from propa!atin! throu!h the network. 8oth cutthrou!h and store-and-forward switches separate a network into collision domains, allowin! network desi!n rules to be e*tended. 3ach of the se!ments attached to an 3thernet switch has a full 95 bps of bandwidth shared b# fewer users, which results in better performance (as opposed to hubs that onl# allow bandwidth sharin! from a sin!le 3thernet). %ewer switches toda# offer hi!h-speed links, +DD", +ast 3thernet or A&. &hese are used to link switches to!ether or !ive added bandwidth to hi!htraffic servers. A network composed of a number of switches linked to!ether via uplinks is termed a ?collapsed backbone? network.

"outers: Routers filter out network traffic b# specific protocol rather than b# packet address.

Routers also divide networks lo!icall# instead of ph#sicall#. An " router can divide a network into various subnets so that onl# traffic destined for particular " addresses can pass between se!ments. %etwork speed often decreases due to this t#pe of intelli!ent forwardin!. 1uch filterin! takes more time than that e*ercised in a switch or brid!e, which onl# looks at the 3thernet address. Iowever, in more comple* networks, overall efficienc# is improved b# usin! routers.

$hat is a network firewall% A firewall is a s#stem or !roup of s#stems that enforces an access control polic# between two networks. &he actual means b# which this is accomplished varies widel#, but in principle, the firewall can be thou!ht of as a pair of mechanisms: one which e*ists to block traffic, and the other which e*ists to permit traffic. 1ome firewalls place a !reater emphasis on blockin! traffic, while others emphasi'e permittin! traffic. robabl# the most important thin! to reco!ni'e about a firewall is that it implements an access control polic#. "f #ou donBt have a !ood idea of what kind of access #ou want to allow or to den#, a firewall reall# wonBt help #ou. "tBs also important to reco!ni'e that the firewallBs confi!uration, because it is a mechanism for enforcin! polic#, imposes its polic# on ever#thin! behind it. Administrators for firewalls mana!in! the connectivit# for a lar!e number of hosts therefore have a heav# responsibilit#.


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Network &esign Criteria: 3thernets and +ast 3thernets have desi!n rules that must be followed in order to function correctl#. a*imum number of nodes, number of repeaters and ma*imum se!ment distances are defined b# the electrical and mechanical desi!n properties of each t#pe of 3thernet and +ast 3thernet media. A network usin! repeaters, for instance, functions with the timin! constraints of 3thernet. Althou!h electrical si!nals on the 3thernet media travel near the speed of li!ht, it still takes a finite time for the si!nal to travel from one end of a lar!e 3thernet to another. &he 3thernet standard assumes it will take rou!hl# <5 microseconds for a si!nal to reach its destination. 3thernet is subject to the ?<-=-7? rule of repeater placement: the network can onl# have five se!ments connectedH it can onl# use four repeatersH and of the five se!ments, onl# three can have users attached to themH the other two must be interrepeater links.

"f the desi!n of the network violates these repeater and placement rules, then timin! !uidelines will not be met and the sendin! station will resend that packet. &his can lead to lost packets and e*cessive resent packets, which can slow network performance and create trouble for applications. +ast 3thernet has modified repeater rules, since the minimum packet si'e takes less time to transmit than re!ular 3thernet. &he len!th of the network links allows for a fewer number of repeaters. "n +ast 3thernet networks, there are two classes of repeaters. Class " repeaters have a latenc# of 5.J microseconds or less and are limited to one repeater per network. Class "" repeaters have a latenc# of 5.= microseconds or less and are limited to two repeaters per network. &he followin! are the distance (diameter) characteristics for these t#pes of +ast 3thernet repeater combinations: %ast Ethernet

&opper

%ier

"o =epeaters

1::m

412m>

ne !lass )

2::m

2?2m

=epeater ne !lass ))

2::m 2:;m

2?2m 22

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=epeater (#o !lass )) =epeaters > 8ull Duple 7ode 2 $m

When conditions reuire !reater distances or an increase in the number of nodes2repeaters, then a brid!e, router or switch can be used to connect multiple networks to!ether. &hese devices join two or more separate networks, allowin! network desi!n criteria to be restored. 1witches allow network desi!ners to build lar!e networks that function well. &he reduction in costs of brid!es and switches reduces the impact of repeater rules on network desi!n. 3ach network connected via one of these devices is referred to as a separate collision domain in the overall network.

T'pes of Ser(ers: De&i$e er&ers A device server is defined as a speciali'ed, network-based hardware device desi!ned

to perform a sin!le or speciali'ed set of server functions. "t is characteri'ed b# a minimal operatin! architecture that reuires no per seat network operatin! s#stem license, and client access that is independent of an# operatin! s#stem or proprietar# protocol. "n addition the device server is a ?closed bo*,? deliverin! e*treme ease of installation, minimal maintenance, and can be mana!ed b# the client remotel# via a Web browser. rint servers, terminal servers, remote access servers and network time servers are e*amples of device servers which are speciali'ed for particular functions. 3ach of these t#pes of servers has uniue confi!uration attributes in hardware or software that help them to perform best in their particular arena.

(rint er&ers


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$rint servers allow printers to be shared b# other users on the network. 1upportin!

either parallel and2or serial interfaces, a print server accepts print jobs from an# person on the network usin! supported protocols and mana!es those jobs on each appropriate printer. rint servers !enerall# do not contain a lar!e amount of memor#H printers simpl# store information in a ueue. When the desired printer becomes available, the# allow the host to transmit the data to the appropriate printer port on the server. &he print server can then simpl# ueue and print each job in the order in which print reuests are received, re!ardless of protocol used or the si'e of the job.

"utiport De&i$e er&ers Devices that are attached to a network throu!h a multiport device server can be shared between terminals and hosts at both the local site and throu!hout the network. A sin!le terminal ma# be connected to several hosts at the same time (in multiple concurrent sessions), and can switch between them. ultiport device servers are also used to network devices that have onl# serial outputs. A connection between serial ports on different servers is opened, allowin! data to move between the two devices. >iven its natural translation abilit#, a multi-protocol multiport device server can perform conversions between the protocols it knows, like $A& and &C2". While server bandwidth is not adeuate for lar!e file transfers, it can easil# handle host-tohost inuir#2response applications, electronic mailbo* checkin!, etc. And it is far more economical than the alternatives of acuirin! e*pensive host software and special-purpose converters. ultiport device and print servers !ive their users !reater fle*ibilit# in confi!urin! and mana!in! their networks. Whether it is movin! printers and other peripherals from one network to another, e*pandin! the dimensions of interoperabilit# or preparin! for !rowth, multiport device servers can fulfill #our needs, all without major rewirin!.

#$$ess er&ers While 3thernet is limited to a !eo!raphic area, remote users such as travelin! sales people need access to network-based resources. Remote $A% access, or remote


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access, is a popular wa# to provide this connectivit#. Access servers use telephone services to link a user or office with an office network. Dial-up remote access solutions such as "1D% or as#nchronous dial introduce more fle*ibilit#. Dial-up remote access offers both the remote office and the remote user the econom# and fle*ibilit# of ?pa# as #ou !o? telephone services. "1D% is a special telephone service that offers three channels, two = Kbps ?8? channels for user data and a ?D? channel for settin! up the connection. With "1D%, the 8 channels can be combined for double bandwidth or separated for different applications or users. With as#nchronous remote access, re!ular telephone lines are combined with modems and remote access servers to allow users and networks to dial an#where in the world and have data access. Remote access servers provide connection points for both dial-in and dial-out applications on the network to which the# are attached. &hese h#brid devices route and filter protocols and offer other services such as modem poolin! and terminal2printer services. +or the remote C user, one can connect from an# available telephone jack (R=<), includin! those in a hotel rooms or on most airplanes.

Network i+e er&ers A network time server is a server speciali'ed in the handlin! of timin! information from sources such as satellites or radio broadcasts and is capable of providin! this timin! data to its attached network. 1peciali'ed protocols such as %& or udp2time allow a time server to communicate to other network nodes ensurin! that activities that must be coordinated accordin! to their time of e*ecution are s#nchroni'ed correctl#. >1 satellites are one source of information that can allow !lobal installations to achieve constant timin!.

IP Addressing: An " ("nternet rotocol) address is a uniue identifier for a node or host connection on an " network. An " address is a 76 bit binar# number usuall# represented as = decimal values, each representin! 4 bits, in the ran!e 5 to 6<< (known as octets) separated b# decimal points. &his is known as ?dotted decimal? notation. 3*ample: [email protected] "t is sometimes useful to view the values in their binar# form.


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9=5 .9J@ .665 .655

95559955.95995599.99599955.99559555 3ver# " address consists of two parts, one identif#in! the network and one identif#in! the node. &he Class of the address and the subnet mask determine which part belon!s to the network address and which part belon!s to the node address.

Address Classes: &here are < different address classes. ou can determine which class an# " address is in b# e*aminin! the first = bits of the " address. Class A addresses be!in with 5***, or 9 to 96 decimal. Class 8 addresses be!in with 95**, or 964 to 9@9 decimal. Class C addresses be!in with 995*, or 9@6 to 667 decimal. Class D addresses be!in with 9995, or 66= to 67@ decimal. Class 3 addresses be!in with 9999, or 6=5 to 6<= decimal. Addresses be!innin! with 59999999, or 96J decimal, are reserved for loopback and for internal testin! on a local machine. Lou can test this: #ou should alwa#s be able to pin! 96J.5.5.9, which points to #ourselfM Class D addresses are reserved for multicastin!. Class 3 addresses are reserved for future use. &he# should not be used for host addresses. %ow we can see how the Class determines, b# default, which part of the " address belon!s to the network (%) and which part belon!s to the node (n). Class A -- %%%%%%%%.nnnnnnnn.nnnnnnn.nnnnnnn


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Class 8 -- %%%%%%%%.%%%%%%%%.nnnnnnnn.nnnnnnnn Class C -- %%%%%%%%.%%%%%%%%.%%%%%%%%.nnnnnnnn "n the e*ample, [email protected] is a Class 8 address so b# default the %etwork part of the address (also known as the %etwork Address) is defined b# the first two octets (9=5.9J@.*.*) and the node part is defined b# the last 6 octets (*.*.665.655). "n order to specif# the network address for a !iven " address, the node section is set to all ?5?s. "n our e*ample, [email protected] specifies the network address for [email protected]. When the node section is set to all ?9?s, it specifies a broadcast that is sent to all hosts on the network. [email protected]<<.6<< specifies the e*ample broadcast address. %ote that this is true re!ardless of the len!th of the node section.

Pri(ate Subnets: &here are three " network addresses reserved for private networks. &he addresses are 95.5.5.524, 9J6.9.5.5296, and [email protected]4.5.529. &he# can be used b# an#one settin! up internal " networks, such as a lab or home $A% behind a %A& or pro*# server or a router. "t is alwa#s safe to use these because routers on the "nternet will never forward packets comin! from these addresses 1ubnettin! an " %etwork can be done for a variet# of reasons, includin! or!ani'ation, use of different ph#sical media (such as 3thernet, +DD", WA%, etc.), preservation of address space, and securit#. &he most common reason is to control network traffic. "n an 3thernet network, all nodes on a se!ment see all the packets transmitted b# all the other nodes on that se!ment. erformance can be adversel# affected under heav# traffic loads, due to collisions and the resultin! retransmissions. A router is used to connect " networks to minimi'e the amount of traffic each se!ment must receive.

u'net "asking Appl#in! a subnet mask to an " address allows #ou to identif# the network and node parts of the address. &he network bits are represented b# the 9s in the mask, and the node bits are represented b# the 5s. erformin! a bitwise lo!ical A%D operation


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between the " address and the subnet mask results in the %etwork Address or %umber.

+or e*ample, usin! our test " address and the default Class 8 subnet mask, we !et: 95559955.95995599.99995555.99559555 [email protected]=5.655 Class 8 " Address 99999999.99999999.55555555.55555555 6<<.6<<.555.555 Default Class 8 1ubnet ask 95559955.95995599.55555555.55555555 [email protected] %etwork Address

&efault subnet )asks: Class A - 6<<.5.5.5 - 99999999.55555555.55555555.55555555 Class 8 - 6<<.6<<.5.5 - 99999999.99999999.55555555.55555555 Class C - 6<<.6<<.6<<.5 - 99999999.99999999.99999999.55555555 C"DR -- Classless "nterDomain Routin!. C"DR was invented several #ears a!o to keep the internet from runnin! out of " addresses. &he ?classful? s#stem of allocatin! " addresses can be ver# wastefulH an#one who could reasonabl# show a need for more that 6<= host addresses was !iven a Class 8 address block of <<77 host addresses. 3ven more wasteful were companies and or!ani'ations that were allocated Class A address blocks, which contain over 9 illion host addressesG Onl# a tin# percenta!e of the allocated Class A and Class 8 address space has ever been actuall# assi!ned to a host computer on the "nternet. eople reali'ed that addresses could be conserved if the class s#stem was eliminated. 8# accuratel# allocatin! onl# the amount of address space that was actuall# needed, the address space crisis could be avoided for man# #ears. &his was first proposed in 9@@6 as a scheme called 1upernettin!.


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&he use of a C"DR notated address is the same as for a Classful address. Classful addresses can easil# be written in C"DR notation (Class A N 24, Class 8 N 29, and Class C N 26=) "t is currentl# almost impossible for an individual or compan# to be allocated their own " address blocks. ou will simpl# be told to !et them from #our "1. &he reason for this is the ever-!rowin! si'e of the internet routin! table. ust < #ears a!o, there were less than <555 network routes in the entire "nternet. &oda#, there are over @5,555. /sin! C"DR, the bi!!est "1s are allocated lar!e chunks of address space (usuall# with a subnet mask of 29@ or even smaller)H the "1Bs customers (often other, smaller "1s) are then allocated networks from the bi! "1Bs pool. &hat wa#, all the bi! "1Bs customers (and their customers, and so on) are accessible via 9 network route on the "nternet. "t is e*pected that C"DR will keep the "nternet happil# in " addresses for the ne*t few #ears at least. After that, "v, with 964 bit addresses, will be needed. /nder "v, even slopp# address allocation would comfortabl# allow a billion uniue " addresses for ever# person on earth

*a)ining 'our network with co))ands: in! "%> is used to check for a response from another computer on the network. "t can tell #ou a !reat deal of information about the status of the network and the computers #ou are communicatin! with. in! returns different responses dependin! on the computer in uestion. &he responses are similar dependin! on the options used. in! uses " to reuest a response from the host. "t does not use &C ."t takes its name from a submarine sonar search - #ou send a short sound burst and listen for an echo - a pin! - comin! back.


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"n an " network, pin!B sends a short data burst - a sin!le packet - and listens for a sin!le packet in repl#. 1ince this tests the most basic function of an " network (deliver# of sin!le packet), itBs eas# to see how #ou can learn a lot from some pin!sB. &o stop pin!, t#pe control-c. &his terminates the pro!ram and prints out a nice summar# of the number of packets transmitted, the number received, and the percenta!e of packets lost, plus the minimum, avera!e, and ma*imum round-trip times of the packets. 1ample pin! session "%> localhost (96J.5.5.9): < data b#tes = b#tes from 96J.5.5.9: icmpPseN5 ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN9 ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN6 ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN7 ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN= ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN< ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseNJ ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN4 ttlN6<< timeN6 ms = b#tes from 96J.5.5.9: icmpPseN@ ttlN6<< timeN6 ms localhost pin! statistics

95 packets transmitted, 95 packets received, 5Q packet loss round-trip min2av!2ma* N 62626 ms meikro The Time To -ive (TT-! field can be interestin!. &he main purpose of this is so that

a packet doesnBt live forever on the network and will eventuall# die when it is deemed ?lost.? 8ut for us, it provides additional information. We can use the &&$ to determine appro*imatel# how man# router hops the packet has !one throu!h. "n this case itBs 6<< minus % hops, where % is the &&$ of the returnin! 3cho Replies. "f the


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&&$ field varies in successive pin!s, it could indicate that the successive repl# packets are !oin! via different routes, which isnBt a !reat thin!.

&he time field is an indication of the round-trip time to !et a packet to the remote host. &he repl# is measured in milliseconds. "n !eneral, itBs best if round-trip times are under 655 milliseconds. &he time it takes a packet to reach its destination is called latenc#. "f #ou see a lar!e variance in the round-trip times (which is called ?jitter?), #ou are !oin! to see poor performance talkin! to the host

NLE/( ")-/0$ is an application that facilitates lookin! up hostnames on the network. "t can reveal the " address of a host or, usin! the " address, return the host name.

"t is ver# important when troubleshootin! problems on a network that #ou can verif# the components of the networkin! process. %slookup allows this b# revealin! details within the infrastructure.

N6# ",T)TAT is used to look up the various active connections within a computer. "t is

helpful to understand what computers or networks #ou are connected to. &his allows #ou to further investi!ate problems. One host ma# be respondin! well but another ma# be less responsive.

($onfig &his is a icrosoft windows %&, 6555 command. "t is ver# useful in determinin! what could be wron! with a network. &his command when used with the 2all switch, reveal enormous amounts of troubleshootin! information within the s#stem. Windows 6555 " Confi!uration Iost %ame . . . . . . . . . . . . : cowder


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rimar# D%1 1uffi* . . . . . . . : %ode &#pe . . . . . . . . . . . . : 8roadcast " Routin! 3nabled. . . . . . . . : %o W"%1 ro*# 3nabled. . . . . . . . : %o W"%1 ro*# 3nabled. . . . . . . . : %o Connection-specific D%1 1uffi* . : Description . . . . . . . . . . . : WA% (21$") "nterface h#sical Address. . . . . . . . . : 55-<7-=<-55-55-55 DIC 3nabled. . . . . . . . . . . : %o " Address. . . . . . . . . . . . : [email protected] 1ubnet ask . . . . . . . . . . . : 6<<.6<<.6<<.6<< Default >atewa# . . . . . . . . . : [email protected]< D%1 1ervers . . . . . . . . . . . : 96.956.6==.6 [email protected]

ra$eroute &raceroute on /ni* and $inu* (or tracert in the icrosoft world) attempts to trace the current network path to a destination. Iere is an e*ample of a traceroute run to www.cumbuco-car-rental.com:  traceroute www.cumbuco-car-rental.com traceroute to amber.www.cumbuco-car-rental.com (964.76.6<.96), 75 hops ma*, =5 b#te packets 9 sf9-e7.wired.net (65[email protected]) 7.97< ms 7.569 ms 7.9 ms 6 sf5-e6s6.wired.net (65<.66J.65.77) 9.46@ ms 7.44 ms 6.JJ6 ms 7 paloalto-cr95.bbnplanet.net ([email protected].95<) <.76J ms =.<@J ms <.J6@ ms = paloalto-br9.bbnplanet.net ([email protected]@7) =.4=6 ms =.9< ms 7.=6< ms


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< sl-sj-6.sprintlink.net (=.5.9.) J.=44 ms 74.45= ms J.J54 ms  9==.676.4.49 (9==.676.4.49) .<5 ms .79 ms .<< ms J 9==.676.=.@J (9==.676.=.@J) J.74 ms J.@=4 ms 4.96@ ms 4 9==.664.9=.<5 (9==.664.9=.<5) @.<5= ms 96.4= ms 9.=4 ms @ f<-5.inr--eva.cumbuco-car-rental.com ([email protected].69) @.J6 ms 95.99 ms 95.=57 ms

95 f5-5.inr-95J-eva.cumbuco-car-rental.com (964.76.6.9) 99.=J4 ms 95.44 ms @.7J ms

99 f4-5.inr-955-eva.cumbuco-car-rental.com (964.76.67<.955) 95.J74 ms 99.@7 ms 96.<65 ms


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Computer Networking and Data Communication Solved Question Paper

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