Networking Interview Question and Answer

7/25/2019 Networking Interview Question and Answer

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Networking Interview Question and Answer

Q1.Comment on Data Encryption Standard (DES) weakness andstrength.

The Data Encryption Standard (DES) is a symmetric key blockcipher which takes 64-bit plaintext and 56-bit key as an inputand produces 64-bit cipher text as output The DES !unction ismade up o! " and S-boxes "-boxes transpose bits and S-boxessubstitute bits to #enerate a cipher

Strength-The stren#th o! DES lies on two !acts$

The use o! 56-bit keys$ 56-bit key is used in encryption%there are &56 possible keys ' brute !orce attack on such number

o! keys is impractical The nature o! al#orithm$ ryptanalyst can per!orm

cryptanalysis by exploitin# the characteristic o! DES al#orithmbut no one has succeeded in !indin# out the weakness

Weakness-eakness has been !ound in the desi#n o! the cipher$

Two chosen input to an S-box can create the same output

The purpose o! initial and !inal permutation is not clear

Q2. I yo! are a "ictim o Denia# o Ser"ice (Dos) then what yo!do$

The !unction o! a denial o! ser*ice attack is to !lood its tar#etmachine with too much tra!!ic and pre*ents it !rom bein#accessible to any other re+uests or pro*idin# ser*ices

To pre*ent DoS attacks !irewall can be con!i#ured as arelay, in this approach the !irewall responds on behal! o! theinternal host Durin# the attack% the !irewall responds to theS. sent by the attacker, since the '/ ne*er arri*es% the!irewall terminates the connection

0y /eepin# protocols and 'nti*irus so!tware up-to-date% wecan pre*ent to be a *ictim o! DoS ' re#ular scannin# o! themachine is also necessary in order to detect any 1anomalous2beha*ior

Q%. What are &r!te 'orce ttacks$
http://dharanyadevi.blogspot.in/2012/06/networking-interview-question-and.htmlhttp://dharanyadevi.blogspot.in/2012/06/networking-interview-question-and.html


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0rute !orcin# is a mechanism which is used by an attacker tobreak the encryption o! data by applyin# a set o! *arious keyryptanalyst has a set o! number o! keys and apply them one byone to the encryption al#orithm until he #et the ri#ht key

Eamp#e*http$33wwwxxxxxcom3online3Displayms#aspms#D7896:

n this example a cryptanalyst may apply brute!orcin# to the*alue o! ms#D and read the user;s datan this the browser re+uestin# !or Displayms#asp pa#e andsendin# ms#D 7896: to the web ser*er

Q+. ,ow do yo! !se S or oth a!thentication and secrecy$

ne can encrypt the hash (?D43S@') o! thedata with a pri*ate key This is known as di#ital si#nature

=or Secrecy$ Secrecy3con!identiality is achie*ed by encryptin#the data with public key and decryptin# with pri*ate key

Q/. Can yo! dierentiate among encoding0 encryption and hashing$

Encodin#$ 0asically encodin# is used to protect the inte#rity o!data as it crosses throu#h communication network to keep itsori#inal messa#e upon arri*in# t is primarily an insecure!unction because it is easily re*ersible

Encryption$ Encryption is basically desi#ned !or con!identialityand data inte#rity and re*ersible only i! you ha*e theappropriate key

@ashin#$ ith hashin# the operation is one-way ie non-

re*ersible t takes an input (or Amessa#e;) and returns a !ixed-siBe strin#% which is called the hash *alue

Q. I yo! ha"e to generate a hash !nction then whatcharacteristics are needed in a sec!re hash !nction$

' secure hash !unction should ha*e the !ollowin# characteristics$


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The SS protocol (Secure Socket ayer protocol) was ori#inallyde*eloped by .etscape% to ensure security o! data transported androuted throu#h @TT"% D'" or ">" application layer

SS uses T" as a communication layer to pro*ide a reliable end-

to-end secure and authenticated connection, which helps internetusers to protect !rom *arious threats SS


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Q12. What are rep#ay attacks$ :i"e an eamp#e o rep#ay attack


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Q1/. What is Symmetric->ey cryptography and symmetric->eycryptography$

Symmetric->ey Cryptography*Symmetric-key crypto#raphy uses asin#le key !or both encryption and decryption Encryption and

decryption al#orithm are in*erse o! each other

Example$

To create the ciphertext !rom the plaintext Gohn uses anencryption al#orithm and a key To create the plaintext !romciphertext% 0ob uses the decryption al#orithm and the same key

symmetric->ey cryptography*t is also called public keycrypto#raphy n public key crypto#raphy two keys$ a pri*ate keyand a public key is used Encryption is done throu#h the publickey and decryption throu#h pri*ate key


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Q1. Ep#ain the c#asses o I3 address

" addresses are or#aniBed into classes =or con*enience o!humans% " addresses are expressed in the decimal !ormat E*erynumber in each class is represented as binary to computers

The !our numbers in an " address are known as Aoctets; Each o!them has ei#ht bit positions The octets are di*ided into twosections$ .et and @ost The !irst octet represents .et !oridenti!yin# the network and the @ost contains the last octetThere are !i*e " classes

C#ass * The class ' is used !or *ery lar#e networks There are :to :&6 are part o! this class That means there are :&6 lass 'networks lass ' networks accounts !or hal! o! the totala*ailable " addresses

C#ass &* t is used !or medium siBe networks The " address witha !irst octet !rom :&8 to :9: is part o! this class lass 0networks ha*e a !irst bit *alue o! : and a second bit *alue o! Hin the !irst octet

C#ass C* lass is used !or small to middle siBe networks "address with a !irst octet starts !rom :9&-&& lass networksha*e a !irst bit *alue o! :% second bit *alue o! : and a thirdbit *alue o! H in the !irst octet

C#ass D* t has !irst% second and third bit *alue as : and the

!ourth bit as H The other &8 bits are used !or identi!yin# the#roup o! computers which is intended !or multicast messa#es

C#ass E* lass E is used !or identi!ication purpose The !ourbits *alue is : The other &8 bits are used !or identi!yin# the#roup o! computers which is intended !or multicast messa#es

Q14. Deine &roadcast0 ?nicast and 9!#ticast.

?nicast* ' term used in communication to describe a piece o!in!ormation to send !rom one point to another There are only

sender and recei*er 'll '.s support unicast trans!er mode andmost applications that employ T" transport protocol uses unicastmessa#in#

&roadcast* ' term used !or describin# communication that is senta piece o! in!ormation !rom one point to all other points Thereis one sender and multiple recei*ers 'll '.s support broadcasttransmission


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9!#ticast* ' term described in communicatin# a piece o!in!ormation sent !rom one or more points to a set o! otherpoints The senders and recei*ers are one or more

Q15. What is @etwork 9ask$

' network mask is used !or determination o! what subnet an "address belon#s to 'n " address has network address and thehost address The !irst two numbers represents the networkaddress and the second two numbers represents the host o! thenetwork

Q27. Deine S!netting.

' subnet describes a set o! networked computers which ha*e common" address routin# pre!ix

0reakin# the networkin# into smaller and more e!!icient subnetsis known as subnets Subnettin# pre*ents Ethernet packetcollision which has excessi*e rates in a lar#e network


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secured data is not leaked 'ccess to this network is limitedomputers usin# trusted networks are more secured andcon!idential because o! stron# !irewalls

?ntr!sted networks* Such networks are usually administered by the

owners They can allow improper access to sensiti*e or personaldata These machines are usually separate Such machines could memore prone to attacks

Q2+. What are the dierent types o B3@$

emote ccess B3@$- 'lso called as Jirtual "ri*ate dial-upnetwork (J"D.) is mainly used in scenarios where remote access toa network becomes essential


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Shi"a 3assword !thentication 3rotoco# (S33)$- t is apassword authentication protocol t is less secure as the sameuser password is always sent in the same re*ersibly encrypted!orm

Q2. What is A!nne#ing$

A!nne#ing is a mechanism pro"ided to transer data sec!re#yetween two networks. Ahe data is sp#it into sma##er packets andpassed thro!gh the t!nne#. Ahe data passing thro!gh the t!nne#has % #ayers o encryption. Ahe data is encaps!#ated. A!nne#ing can e approached y 3oint to 3oint t!nne#ing protoco#Q2.What are "o#!ntary and comp!#sory t!nne#s$

Bo#!ntary A!nne#ing

Isers computer is an end point o! the tunnel and acts as tunnelclient @ere the client or user issues a re+uest to con!i#ure andcreate a *oluntary tunnel They re+uire a dial up or '.

connection Example o! dial up connection is internet at homewhere a call is made to the S" and connection is obtained

Comp!#sory t!nne#ingn compulsory tunnelin#% instead o! the user a *pn remote accessser*er con!i#ures and creates a tunnel @ence% the end point isthe


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Q%1. What is A3$


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Extension header$ - !irst & bit word contains pro!ile speci!icidenti!ier and len#th speci!ier

Ahe %2 its o AC3 header ormat is as o##ows*- (6 to )

0it H-:$- ndicates *ersion% currently &

0it &$- "- indicates paddin# bytes0it to 7$- ount o! number o! reception report blocks0it 8 to :5$- Type$ - Determined


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ithin campus and o!!ices% usin# multicastin# !iledistribution can be done

System messa#es% news and *ideos can be sent at the sametime

?ore commonly used !or audio and *ideo streamin#

Q%4. What are Sockets$ ,ow do Sockets Work$

' socket is used to connect an application to a network protocol' socket enables communication between a client and a ser*er Thecommunication is started when the client is assi#ned a local portnumber% and binds a socket to it The client writes on the socketand #ets in!ormation !rom ser*er by readin# it The Socket classis used to communicate t pro*ides rich set o! methods !or bothasynchronous and synchronous data trans!er onnect'synch is usedto start an asynchronous connection Send'synch and


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Q+2. What are the two important AC3 Socket c#asses$ Ep#ain them

The two most important socket lasses are$

Socket C#ass*The Socket class pro*ides enriched methods and

properties !or network communications t allows both synchronousand asynchronous data trans!er Shutdown method should be used toend the Socket once the data trans!er is complete Isin#SetSocket>ption the socket can be con!i#uredDeclaration$

"ublic lass Socket Nmplements Disposable

Ser"er Socket C#ass*The ser*er Socket class is used toimplement ser*er sockets Ser*er sockets are used to respond tore+uests recei*ed o*er the network

Q+%.What are the ad"antages and disad"antages o a"a Sockets$

d"antages*

=lexible and power!ul

ause low network tra!!ic i! e!!iciently used

>nly updated in!ormation can be sent

Disad"antages*

The Ga*a applets can establish communication only with themachine re+uested and not with any other machine on the network

Sockets allow only raw data to be sent This means that bothclient and ser*er need to ha*e mechanisms to interpret the data

Q++. What is race condition$ ,ow does the race condition occ!r$

' race condition occurs when there are two or more processestryin# to access the same data concurrently or per!ormin# thesame operation concurrently >utput o! the operation depends onthe se+uence o! re+uests o! the operations

n networkin#% a race condition occurs when two or more try toaccess the same channel This usually occurs in networks ha*in#la# times

n a computer memory% a race condition occurs when a re+uest toread and write data is recei*ed at the same time


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n lo#ic #ates% a race condition occurs when some inputsencounter con!licts

Q+/. What is meant y Symmentric 9!#tiprocessing (S93)$

Symmetric ?ultiprocessin# allows any processor to do work o!another processor S?" allows multiple processors to processpro#rams that are a part o! common >S and memory ?ost commonexample o! S?" is >T" where many users access the same databasein a relati*ely simple set o! transactions S?" e!!icientlybalances the workload o! the processors

Q+. What are A3-6ite and A3-,ea"y 9onitors$

T" K ite is an inte#ration o! T" ?onitor !unctions in a databaseen#ine T"-@ea*y ?onitor allows the machine to initiate somecomplex multi ser*er transactions T" @ea*y monitors supportclient ser*er architecture

Q+. Dierence etween the comm!nication and transmission.

The di!!erences between the communication and transmission are$

"hysical mo*ement o! in!ormation and concernin# about bitpriority% synchroniBation% clock etc is re!erred as transmission%where as !ull exchan#e o! in!ormation amon# media o!communication is re!erred as communication

Transmission is all about transmittin# o! data to thedestination% where as the dialo#ue between the source anddestination is all about communication

Q+4.What is the dierence etween A'A3 and 'A3 app#ication #ayerprotoco#s$

The di!!erences between =T" and T=T"$

=T" is connection oriented% where as T=T" is notT=T" uses error checkin# and !low control% where as T=T" does not

cause error checkin#

=T" uses T" as transport protocol% where as T=T" uses ID" astransport protocol'uthentication is mandatory in =T"% where as authentication isnot needed in T=T"


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Gust #ettin# and puttin# application e!!ecti*ely is the desi#nconcern o! T=T"% where as =T" pro*ides more control and dataconnection aspects

Q+5. Dierence etween it rate and a!d rate.

The di!!erences between bit rate and baud rate$

0it rate is measured as number o! data bits transmitted 3 secondin communication channel

0aud rate is measured as number o! times a si#nal state ischan#ed in a communication channel

>ne chan#e o! state can transmit one bit or less than one bitwhich depends on modulation techni+ue used The bit and baud rateha*e the connection$

bps baud 3 second x the number o! bits 3 per baud

Q/7. What are @EA&IS and @EA&E?I$

.etwork 0asic nput >utput System pro*ides session layer o! >Smodel related ser*ices which allows the applications on di!!erentcomputers !or communicatin# o*er a '. .et0>S runs o*er T"3"throu#h .et0>S o*er T"3" (.0T) protocol This process resultsin e*ery computer in the network with .et0>S name and an "address that corresponds to a host name

.et0>S Extended Iser nter!ace is an extended *ersion o!

.et0>S t is a pro#ram that allows computers to communicatewithin a local area network .et0EI !orms the !rame !ormat whichwas not a speci!ication o! .et0>S .et0EI is the best choice!or per!ormin# communication within a '.

Q/1. Dierence etween 3 and 3.

The di!!erences between '


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" address o! destination to physical address con*ersion is doneby '


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application ?>? per!orms this by allowin# an application to bedistributed o*er plat!orms o! di!!erent kind ?>? reduces theapplication de*elopment complexity which spans multiple operatin#systems and network protocols This process insulates theapplication de*eloper !rom the operatin# systems details and

network inter!aces Jarious '"s across di*erse plat!orms andnetworks are pro*ided by ?>?

Q//. What is :ro!pware ser"er$

Mroupware ser*er is so!tware that allows the collaboration o!users% irrespecti*e o! location throu#h the internet or intranetto work to#ether in an atmosphere which is *irtual

Q/. What are A3-6ite and A3-,ea"y 9onitors$

A3-6ite 9onitor*The inte#ration o! T" monitors !unctions in adatabase en#ines is called as T"-ite monitor

A3-,ea"y 9onitor*' T" monitor that supports the client3ser*erarchitecture and allows " !or initiatin# *ery complexmultiser*er transaction !rom the desktop

Q/. What is pp#ication #ayer$

The application layer is located at the top o! the T"3"protocol layers This one contains the network applications whichmake it possible to communicate usin# the lower layers The

so!tware in this layer there!ore communicates usin# one o! thetwo protocols o! the layer below (the transport layer)% ie T"or ID" n computer networkin#% an application layer !irewall isa !irewall operatin# at the application layer o! a protocolstackO:P Menerally it is a host usin# *arious !orms o! proxyser*ers to proxy tra!!ic instead o! routin# it 's it works onthe application layer% it may inspect the contents o! thetra!!ic% blockin# what the !irewall administrator *iews asinappropriate content% such as certain websites% *iruses% andattempts to exploit known lo#ical !laws in client so!tware% andso !orth 'n application layer !irewall does not route tra!!ic on

the network layer 'll tra!!ic stops at the !irewall which mayinitiate its own connections i! the tra!!ic satis!ies the rules

Q/4. Deine D@S

The D.S translates nternet domain and host names to "addresses D.S automatically con*erts the names we type in oureb browser address bar to the " addresses o! eb ser*ers


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hostin# those sites D.S implements a distributed database tostore this name and address in!ormation !or all public hosts onthe nternet

Q/5. Deine Ae#net

Telnet is the main nternet protocol !or creatin# a connection toa remote ser*er

Q7. Deine S9A3.

S?T" - Short !or Simple ?ail Trans!er "rotocol% a protocol !orsendin# e-mail messa#es between ser*ers

Q1. What Is a 9C ddress$

?' (?edia 'ccess ontrol) addresses are #lobally uni+ueaddressed that are written into hardware at the time o!manu!acture The ?' address is a uni+ue *alue associated with anetwork adapter ?' addresses are also known as hardwareaddresses or physical addresses They uni+uely identi!y anadapter on a '. ?' addresses are :&-di#it hexadecimal numbers(48 bits in len#th)

Q2. 9C "s. I3 ddressing

hereas ?' addressin# works at the data link layer% "addressin# !unctions at the network layer (layer ) tQs asli#ht o*ersimpli!ication% but one can think o! " addressin# assupportin# the so!tware implementation and ?' addresses assupportin# the hardware implementation o! the network stack The?' address #enerally remains !ixed and !ollows the networkde*ice% but the " address chan#es as the network de*ice mo*es!rom one network to another

Q%. Deine Spanning-Aree 3rotoco# (SA3)

Spannin#-Tree "rotocol (ST") as de!ined in the EEE 8H&:D is alink mana#ement protocol that pro*ides path redundancy while

pre*entin# undesirable loops in the network =or an Ethernetnetwork to !unction properly% only one acti*e path can existbetween two stations oops occur in networks !or a *ariety o!reasons The most common reason you !ind loops in networks is theresult o! a deliberate attempt to pro*ide redundancy - in caseone link or switch !ails% another link or switch can take o*er

Q+. What is B3@$


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Jirtual "ri*ate network is a network that used the publictelecommunication in!rastructure This means that it used publicwires to connect the nodes E# nternet J". supports remoteaccess to computers and allow data to be transmitted o*er thispublic network E*en thou#h the data is transmitted o*er a public

network% encryption and decryptin# data to ensure security

Q/. ,ow wo!#d yo! deine I3 address$

" address or nternet "rotocol address is the address o! ade*ice attached to an " network (T"3" network) t is a must!or e*ery client% ser*er and network de*ice to ha*e a uni+ue "address !or each network connection (network inter!ace) E*ery "packet contains a source " address and a destination " address's a de*ice mo*es !rom one network to another% its " addresschan#es

Q. Dierence etween Static and Dynamic I3.

Static " is also called as permanent address assi#ned to eachde*ice in a network% whereas Dynamic "% a temporary addressassi#ned to the de*ice *ia D@" so!tware " address assi#ned toyour ser*ice by your cable or DS nternet pro*ider is typicallydynamic " n routers and operatin# systems% the de!aultcon!i#uration !or clients is dynamic "

Q. What is the dierence etween p!#ic and pri"ate I3$

' public " address allows e+uipment accessible to e*eryone onthe internet ' pri*ate " address is !or pri*ate use within thenetwork and allows many more "s to be connected ! you areusin# a pri*ate " and wants J>"% you need to chan#e to a public" address

Q4. What is @etwork ddress Arans#ation$

.etwork 'ddress Translation acts as an a#ent between the nternetand a local network t is a dynamic method which is used tominimiBe nternet connecti*ity needs .etwork address translation

describes the rewritin# o! the nternet "rotocol (") addresseso! data packets so that multiple transmissions re+uire only one" address

Q5. Deine I3 m!#ticast.


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" multicast technolo#y reduces tra!!ic by sendin# stream o!in!ormation to many recipients at one #o Jideo con!erencin#%stock +uotas are the examples based on " multicast

Q7. What is s!neting$

Subnet adds one le*el to the way " address is represented tlo#ically or#aniBes the network =or instance% it can lo#ically#roup computers belon#s to the !inance department

Q1. Deine ddress eso#!tion 3rotoco#.

'ddress


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Q/. Ep#ain how names are trans#ated (reso#"ed) into I3 address.

Domain .ame ser*er or D.S is used to resol*e names into "addresses hen a web address is entered into the browser% theD.S client sends a re+uest to the D.S ser*er to !ind the

correspondin# " address !or the name The D.S ser*er recei*esthis re+uest and searches !or the correspondin# " address in thedatabase ! at this point the resolution !ails% this ser*ersends this re+uest to the parent ser*er The re+uest keeps #oin#up the hierarchy to the parent ser*ers or the closestauthoritati*e o! the D.S ser*er to resol*e the address ! there+uest times out an error is retuned to the client ! theser*er is able to resol*e the name re+uested% it passes thein!ormation back to the client The next re+uest sent by theclient is to re+uest !or a web pa#e !or the " address

Q. Descrie the asics o internet ro!ting.

hen a source sends a packet to a destination% this packet has aspeci!ic path or route it !ollows Di!!erent routin# protocolsare used to !ind the shortest path to the destination Theprotocols maintain routin# tables


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included as part o! the network switch and is located at a#ateway% includin# each point-o!-presence on the nternet Therouter is connected to at least two networks and determines whichway to send each in!ormation packet based on its understandin# o!the state o! the networks it is connected to

Q47. Deine gateway

' #ateway is a network point that pro*ides entrance into anothernetwork >n the nternet% a node or stoppin# point can be eithera #ateway node or a host (end-point) node 0oth the computers o!nternet users and the computers that ser*e pa#es to users arehost nodes The computers that control tra!!ic within yourcompanyQs network or at your local nternet ser*ice pro*ider(S") are #ateway nodes

Q41. What is irewa##$

' !irewall is a hardware or so!tware installed to pro*idesecurity to the pri*ate networks connected to the internet Theycan be implemented in both hardware and so!tware% or acombination o! both 'll data enterin# or lea*in# the ntranetpasses throu#h the !irewall which allows only the data meetin#the administrators; rules to pass throu#h it

Q42. What are the types o irewa##s$

3acket 'i#tering 'irewa##*

This type o! =irewall detects packets and block unnecessarypackets and makes network tra!!ic release

Screening o!ter 'irewa##s*

tQs a so!tware base !irewall a*ailable in


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Q4%. What is Data encryption$

Data encryption ensures data sa!ety and *ery important !orcon!idential or critical data t protect data !rom bein# read%altered or !or#ed while transmission

Q4+. What is the 3!#ic >ey Encryption$

"ublic key encryption use public and pri*ate key !or encryptionand decryption n this mechanism% public key is used to encryptmessa#es and only the correspondin# pri*ate key can be used todecrypt them To encrypt a messa#e% a sender has to knowrecipient;s public key

Q4/. Deine Digita# Signat!res.

Di#ital si#nature is an attachment to an electronic messa#e used!or security purpose t is used to *eri!y the authenticity o!the sender

Q4. What is Ethernet techno#ogy$

Ethernet technolo#y is a hi#h speed broadcast bus technolo#y nthis type% all the station shares a sin#le ether channel andrecei*es e*ery sin#le transmitted si#nal

Q4. Ep#ain the !se o network interace card0 @IC.

. is used to connect computer to an Ethernet network

Q44. Ep#ain token ring techno#ogy.

n this technolo#y% all the de*ices are arran#ed in a circle 'token mo*es around the circular network ' de*ice waits !or thetoken be!ore it sends its !rame >nce it recei*es token% itinitiates transmission o! its !rame

Q45. What is CS9 and CD concept$

n SD' (carrier sense multiple access)% presence o! any di#italsi#nal in a network is checked be!ore transmission Datatransmission occurs only when no si#nal is sensed

D% ollision detection is responsible !or monitorin# carrier inorder to a*oid si#nal Cam

Q57. What is @et&IS protoco#$


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.et0>S (.etwork 0asic nput3>utput System) "rotocol allowsapplications on separate computers to communicate o*er a '. truns o*er T"3" #i*in# each computer in the network a .et0>Sname and " address E# t can be used !or computers runnin#indows &HHH (or be!ore) to Coin a computer network runnin#

indows &HHH (or later

Q51. What is I:93 protoco#$

nternet Mroup ?ana#ement "rotocol% allows internet hosts tomulticast ie to send messa#es to a #roup o! computers Theremay be a #roup o! internet hosts interested to multicast M?"allows router to determine which host #roups ha*e members on a#i*en network se#ment t helps to establish #roup membershipst is commonly used !or streamlinin# *ideos and #amin# Theprotocol can be implemented both as a host side and router sideThe host side is responsible to noti!y its membership in a #roupThe noti!ication is made to a local router This local router(router side) in turn sends out +ueries

Q52. What is AC3 I3 protoco#$

Transmission ontrol "rotocol 3 nternet "rotocol$ - t is a!amily o! protocols used !or communication and connection betweenhosts on the internet t is the most widely used standard !ortransmittin# data o*er the internet The !our layers in theprotocol are (!rom bottom to top)$- "hysical layer% Data linklayer% .etwork layer% transport layer and application layer% also

called as the >S model n T"3" % " is responsible !or!orwardin# packets while T" ensures the correct deli*ery o! data!rom client to ser*er T" detects loss o! data as well

Q5%. What is ,AA3 (,ypertet Aranser 3rotoco#)$

@TT" or @yper Text Trans!er "rotocol is pro*ides a set o! rulesto trans!er !iles% *ideos% ima#es o*er the world wide web henthe web browser is opened% a @TT" re+uest call is made ' webser*er contains a @TT" daemon This daemon is used to wait !or@TT" re+uests and handle them when they arri*e The web browser

!rom where @TT" re+uests are made is called as a client Thesere+uests are sent to the ser*er t uses a reser*ed port no 8H

Q5+. What is @@A3 (@etwork @ews Aranser 3rotoco#)$

..T" or .etwork .ews Trans!er "rotocol is used to mana#e thenotes posted on Inset news#roup (a collection o! posted notes ona subCect posted by di!!erent users) ..T" ser*ers are


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responsible !or mana#in# Isenet news#roup collected #lobally '.TT" client is a part o! the web browser also called as a newsreader t uses a reser*er port no ::9

Q5/. What is 33% (3ost ice 3rotoco# %)$

">" or "ost >!!ice 0ox is used !ro recei*in# emails t is aclient ser*er protocol which holds the email >nce the email isdownloaded !rom the ser*er% ">" deletes it !rom the ser*er>rdinal numbers are used to identi!y speci!ic messa#es

Q5. What is S@93 (Simp#e @etwork 9anagement 3rotoco#)$

S.?" or Simple .etwork ?ana#ement "rotocol is typically used !ormana#in# the network ?ana#in# the network includes mana#in# thenodes present in the network These nodes may be ser*er% routers%brid#es and hubs S.?" a#ents are used to achie*e this ?ana#in#the network is essential because it helps to monitor networkper!ormance% detect network !aults or !ailures% audit networkusa#e etc the S.?" messa#es like T


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Distance here could be the hops The three di!!erent types o!Distance Jector routin# protocols include$- S model

Network Protocol Interview Question andAnswers

3AC6 I@AEBIEW Q?ESAI@S

Q1.What is @et&IS protoco#$

.et0>S (.etwork 0asic nput3>utput System) "rotocol allowsapplications on separate computers to communicate o*er a '. truns o*er T"3" #i*in# each computer in the network a .et0>Sname and " address E# t can be used !or computers runnin#indows &HHH (or be!ore) to Coin a computer network runnin#indows &HHH (or later)

Q2. What is I:93 protoco#$

nternet Mroup ?ana#ement "rotocol% allows internet hosts tomulticast ie to send messa#es to a #roup o! computers Theremay be a #roup o! internet hosts interested to multicast M?"allows router to determine which host #roups ha*e members on a#i*en network se#ment t helps to establish #roup memberships
http://dharanyadevi.blogspot.in/2012/06/network-protocol-interview-question-and.htmlhttp://dharanyadevi.blogspot.in/2012/06/network-protocol-interview-question-and.htmlhttp://dharanyadevi.blogspot.in/2012/06/network-protocol-interview-question-and.htmlhttp://dharanyadevi.blogspot.in/2012/06/network-protocol-interview-question-and.html


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t is commonly used !or streamlinin# *ideos and #amin# Theprotocol can be implemented both as a host side and router sideThe host side is responsible to noti!y its membership in a #roupThe noti!ication is made to a local router This local router(router side) in turn sends out +ueries

Q%. What is AC3 I3 protoco#$

Transmission ontrol "rotocol 3 nternet "rotocol$ - t is a!amily o! protocols used !or communication and connection betweenhosts on the internet t is the most widely used standard !ortransmittin# data o*er the internet The !our layers in theprotocol are (!rom bottom to top)$- "hysical layer% Data linklayer% .etwork layer% transport layer and application layer% alsocalled as the >S model n T"3" % " is responsible !or!orwardin# packets while T" ensures the correct deli*ery o! data!rom client to ser*er T" detects loss o! data as well

Q+. What is ,AA3 (,ypertet Aranser 3rotoco#)$

@TT" or @yper Text Trans!er "rotocol is pro*ides a set o! rulesto trans!er !iles% *ideos% ima#es o*er the world wide web henthe web browser is opened% a @TT" re+uest call is made ' webser*er contains a @TT" daemon This daemon is used to wait !or@TT" re+uests and handle them when they arri*e The web browser!rom where @TT" re+uests are made is called as a client Thesere+uests are sent to the ser*er t uses a reser*ed port no 8H

Q/. What is @@A3 (@etwork @ews Aranser 3rotoco#)$

..T" or .etwork .ews Trans!er "rotocol is used to mana#e thenotes posted on Inset news#roup (a collection o! posted notes ona subCect posted by di!!erent users) ..T" ser*ers areresponsible !or mana#in# Isenet news#roup collected #lobally '.TT" client is a part o! the web browser also called as a newsreader t uses a reser*er port no ::9

Q. What is 33% (3ost ice 3rotoco# %)$

">" or "ost >!!ice 0ox is used !ro recei*in# emails t is aclient ser*er protocol which holds the email >nce the email isdownloaded !rom the ser*er% ">" deletes it !rom the ser*er>rdinal numbers are used to identi!y speci!ic messa#es

Q. What is S@93 (Simp#e @etwork 9anagement 3rotoco#)$


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S.?" or Simple .etwork ?ana#ement "rotocol is typically used !ormana#in# the network ?ana#in# the network includes mana#in# thenodes present in the network These nodes may be ser*er% routers%brid#es and hubs S.?" a#ents are used to achie*e this ?ana#in#the network is essential because it helps to monitor network

per!ormance% detect network !aults or !ailures% audit networkusa#e etc the S.?" messa#es like T


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Q11. What is AC3 protoco#$

Transmission control "rotocol is used to establish communicationbetween nodes or networks and exchan#e data packets t#uarantees deli*ery o! data packets in the order they were sent

@ence it is most commonly used in all applications that re+uire#uaranteed deli*ery o! data t can handle both timeouts (i!packets were delayed) and retransmission (i! packets were lost)The stream o! data is transmitted in se#ments The se#ment headeris & bit it is a connectionless communication protocol at thethird le*el (network) o! the >S model

Q12. AC3 "s. ?D3.

T" #uarantees the deli*ery o! data ID" on the other hand% doesnot #uarantee deli*ery o! data T" deli*ers messa#es in theorder they were sent ID" has no orderin# mechanisms n T" datais sent as a stream while ID" sends data as indi*idual packetsID" is !aster than T" T" is a connection oriented protocolwhile ID" is connectionless

Q1%. What is ?D3 protoco#$

Iser Data "rotocol is a communication protocol t is normallyused as an alternati*e !or T"3" @owe*er there are a number o!di!!erences between them ID" does not di*ide data into packets'lso% ID" does not send data packets in se+uence @ence% theapplication pro#ram must ensure the se+uencin# ID" uses port

numbers to distin#uish user re+uests t also has a checksumcapability to *eri!y the data

Q1+. What is AC3 windowing concept$

T" windowin# concept is primarily used to a*oid con#estion inthe tra!!ic t controls the amount o! unacknowled#ed data asender can send be!ore it #ets an acknowled#ement back !rom therecei*er that it has recei*ed it

Q1/. What is Ar!sted and ?ntr!sted @etworks$

Trusted networks:Such .etworks allow data to be trans!erredtransparently The machines usin# a trusted network are usuallyadministered by an 'dministrator to ensure that pri*ate andsecured data is not leaked 'ccess to this network is limitedomputers usin# trusted networks are more secured andcon!idential because o! stron# !irewalls


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Untrusted networks:Such networks are usually administered by theowners They can allow improper access to sensiti*e or personaldata These machines are usually separate Such machines could memore prone to attacks

Q1. What are the dierent types o B3@$

emote ccess B3@$- 'lso called as Jirtual "ri*ate dial-upnetwork (J"D.) is mainly used in scenarios where remote access toa network becomes essential


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Q14. What is A!nne#ing$

Tunnelin# is a mechanism pro*ided to trans!er data securelybetween two networks The data is split into smaller packets andpassed throu#h the tunnel The data passin# throu#h the tunnel

has layers o! encryption The data is encapsulated Tunnelin#can be approached by "oint to "oint tunnelin# protocol

Q15. What are "o#!ntary and comp!#sory t!nne#s$

Voluntary Tunneling

Isers computer is an end point o! the tunnel and acts as tunnelclient @ere the client or user issues a re+uest to con!i#ure andcreate a *oluntary tunnel They re+uire a dial up or '.connection Example o! dial up connection is internet at homewhere a call is made to the S" and connection is obtained

Compulsory tunneling

n compulsory tunnelin#% instead o! the user a *pn remote accessser*er con!i#ures and creates a tunnel @ence% the end point isthe


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would only be multicast to smaller distance destinations ?orethe *alue o! TT% more would be the scope o! transmission to alar#er number o! machines 'dministrati*e scopin# is anothermechanism n this% transmission is restricted to a speci!icaddress space o! an or#aniBation or a site

Q24. What are the asic components o ro!ters$

Components o o!ter*

Internal components:

?$- Ised to store the routers bootstrap details% operatin#system so!tware

=lash memory$ - holds the operatin# systems ima#es Thecontent is retained when the router is restarted

S stands !or >pen Systems nterconnection

The >S re!erence model #i*es an o*er*iew o! the layeredcommunications and computer network protocol desi#n

The layers o! the >S are$

'pplication ayer "resentation ayer

Session ayer

Transport ayer

.etwork ayer

Data ink ayer


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"hysical ayer

Q%7. Ep#ain dierent #ayers in the SI mode#.

Application Layer:

losest to the end user

nteract directly with the so!tware application

Presentation Layer:

Translates application to network !ormat% and *ice *ersa

orks to trans!orm data into the !orm that the applicationlayer can accept

=ormats and encrypts data to be sent across a network

Session Layer

ontrols the connections between computers

Establishes% mana#es and terminates the connections betweenthe local and remote application

"ro*ides !ull-duplex% hal!-duplex% or simplex operation

Establishes checkpointin#% adCournment% termination% andrestart procedures

Transport Layer:

"ro*ides transparent trans!er o! data between end users

"ro*idin# reliable data trans!er ser*ices to the upperlayers

ontrols the reliability o! a #i*en link throu#h !lowcontrol% se#mentation 3 dese#mentation% and error control

etwork Layer

"ro*ides the !unctional and procedural means o! trans!errin#*ariable len#th data se+uences !rom a source to a destination *iaone or more networks

"er!orms networkroutin# !unctions

"er!orms !ra#mentation and reassembly% and report deli*eryerrors

!ata Link Layer


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"ro*ides the !unctional and procedural means to trans!erdata between network entities

Detects and corrects errors that occur in the "hysicalayer

P"ysical Layer:

De!ines the electrical and physical speci!ications !orde*ice

Q%1. Ep#ain the concept and capai#ities o ?nicast I3 ddresses

t is an " address that uni+uely identi!ies a host in anetworkThe data#ram with a unicast " address is recei*ed and processedby only a sin#le host

Q%2. What is o!ting ta#e$

' routin# table stores the routes o! the *arious nodes in anetwork .odes can be any electronic de*ice connected to thenetwork The table is usually stored in a router or the networkcomputer as a database or !ile This in!ormation helps to !ondthe best possible path The routin# table has at least !ields$the destination network id% cost o! the path% next hop or addressto send the packet

Q%%. What is o!ting 3rotoco#s$


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The Distance Jector protocol initially prepares a


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hereas ?' addressin# works at the data link layer% "addressin# !unctions at the network layer (layer ) tQs asli#ht o*ersimpli!ication% but one can think o! " addressin# assupportin# the so!tware implementation and ?' addresses assupportin# the hardware implementation o! the network stack The

?' address #enerally remains !ixed and !ollows the networkde*ice% but the " address chan#es as the network de*ice mo*es!rom one network to anotherQ+7.Deine Spanning-Aree 3rotoco# (SA3)

Spannin#-Tree "rotocol (ST") as de!ined in the EEE 8H&:D is alink mana#ement protocol that pro*ides path redundancy whilepre*entin# undesirable loops in the network =or an Ethernetnetwork to !unction properly% only one acti*e path can existbetween two stations oops occur in networks !or a *ariety o!reasons The most common reason you !ind loops in networks is theresult o! a deliberate attempt to pro*ide redundancy - in caseone link or switch !ails% another link or switch can take o*er

Q+1. What is B3@$

' J". is a ser*ice that o!!ers secure% reliable connecti*ity o*era shared public network in!rastructure such as the nternet J".smaintain the same security and mana#ement policies as a pri*atenetwork They are the most cost e!!ecti*e method o! establishin#a *irtual point-to-point connection between remote users and anenterprise customerQs network

Q+2. Deine roadcast domain.

t is a lo#ical area in a computer network where any computerconnected to the network can directly transmit to any othercomputer in the domain without ha*in# to #o throu#h a routin#de*ice

Q+%. &ridge "s switch

' brid#e connects two di!!erent '. networks ' switch issomethin# like you can connect many computers to a switch and

then one computer can connect to another throu#h the switchSwitch is a unicast one to one connection

Q++. Deine gateway

' #ateway is a network point that pro*ides entrance into anothernetwork >n the nternet% a node or stoppin# point can be eithera #ateway node or a host (end-point) node 0oth the computers o!


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nternet users and the computers that ser*e pa#es to users arehost nodes The computers that control tra!!ic within yourcompanyQs network or at your local nternet ser*ice pro*ider(S") are #ateway nodes

Q+/. What is irewa##$

' !irewall is a hardware or so!tware installed to pro*idesecurity to the pri*ate networks connected to the internet Theycan be implemented in both hardware and so!tware% or acombination o! both 'll data enterin# or lea*in# the ntranetpasses throu#h the !irewall which allows only the data meetin#the administrators; rules to pass throu#h it

Q+. What are the types o irewa##s$

Packet #iltering #irewall:

This type o! =irewall detects packets and block unnecessarypackets and makes network tra!!ic release

Screening $outer #irewalls:

tQs a so!tware base !irewall a*ailable in peratin#System like indows and I.F

'ardware &ase #irewall:

ts de*ice like box allows stron# security !rom public network?ostly used by bi# networks

Proxy Ser(er:

"roxy ser*er allows all clients to access nternet with di!!erentaccess limits "roxy ser*er has its own !irewall which !iltersthe all packet !rom web ser*er

Q+. Deine Digita# Signat!res.

Di#ital si#nature is an attachment to an electronic messa#e used!or security purpose t is used to *eri!y the authenticity o!the sender

Q+4. What is Ethernet techno#ogy$


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Ethernet technolo#y is a hi#h speed broadcast bus technolo#y nthis type% all the station shares a sin#le ether channel andrecei*es e*ery sin#le transmitted si#nal

Q+5. Ep#ain the !se o network interace card0 @IC.

. is used to connect computer to an Ethernet network

Q/7. Ep#ain token ring techno#ogy.

n this technolo#y% all the de*ices are arran#ed in a circle 'token mo*es around the circular network ' de*ice waits !or thetoken be!ore it sends its !rame >nce it recei*es token% itinitiates transmission o! its !rame

Q/1. What is CS9 and CD concept$

n SD' (carrier sense multiple access)% presence o! any di#italsi#nal in a network is checked be!ore transmission Datatransmission occurs only when no si#nal is sensed D% ollisiondetection is responsible !or monitorin# carrier in order to a*oidsi#nal Cam

Networking Interview Question and Answer

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