SRId KRISHNAd COLLEGEd OFdENGINEERINGdANDd
TECHNOLOGY
20EC925d–
INFORMATIONdSECUIRTYdQUESTIONdBANKddWITHdEVALU
ATIONdSCHEME
MODULEdI-PARTdA
Whatd ared thed threed criteriad necessaryd ford and effectived andd efficientd network?dT C925.1 2
hedmostdimportantdcriteriadaredperformance,dreliabilitydanddsecurity.dPerformancedofdth
ednetworkddependsdondnumberdofdusers,dtypedofdtransmissiondmedium,dthe
capabilitiesdofdthedconnecteddh/wd anddthed efficiencydofdtheds/w.dReliabilitydis
measureddbydfrequencydofdfailure,dthedtimeditdtakesdadlinkdtodrecoverdfromdthedfailuredan
ddthednetwork’sdrobustnessdindadcatastrophe.dSecuritydissuesdincludeprotectingddatadfro
mdunauthorizeddaccessdanddviruses.
GroupdthedOSIdlayersdbydfunction. C925.1 2
ThedsevendlayersdofdthedOSIdmodeldbelongingdtodthreedsubgroups.dNetworkdsupport
d layers:d ConsistingdofdPhysical,d datad linkd andd networkdlayersd andd theyddealdwithd
thedphysicaldaspectsdofdmovingdatadfromdoneddevicedtodanother.dUserdsupportd layer
s:d Consistsd ofd Session,d presentationd andd applicationd layersd anddtheyd allowd int
eroperabilityd amongd unrelatedd softwared systems.d Thed transport
layerdensuresd end-to-endd reliableddatad transmission
Whatdaredthedfeaturesdprovideddbydlayering? C925.1 2
• Itddecomposesdthedproblemdofdbuildingdadnetworkdintodmoredmanageabledc
omponents.dRatherdthandimplementingdadmonolithicdpiecedofdsoftwaredthatd
doesdeverythingd implementdseveraldlayers,deachdofdwhichdsolvesdonedpartdo
fdthedproblem.
• Itdprovidesdmoredmodularddesign.dTodadddsomednewdservice,ditdisdenoughdt
odmodifydthedfunctionalitydatdonedlayer,dreusingdthedfunctionsdprovided
atdalldthedotherdlayers.
Whatdaredthedtwodinterfacesdprovideddbydprotocols? C925.1 2
• Servicedinterface
• Peerdinterface
• Servicedinterface-
definesdthedoperationsdthatdlocaldobjectsdcandperformdondthedprotocol.
• Peerdinterface-
definesdthedformdanddmeaningdofdmessagesdexchangeddbet
weenprotocoldpeersdtodimplementdthe
communicationd service.
WhatdisdLAN? C925.1 2
AdLANdisdadcommondnameduseddtoddescribedadgroupdofddevicesdthatdsharedadgeographic
dlocation.LANdisdlimiteddtodsingledbuildingdordcampus.
WhatdisdflowdControl? C925.1 2
Flowd controld refersd tod ad setd ofd proceduresd usedd tod restrictd thed amountd ofd data.
Thedsenderdcand senddbeforedwaitingdfordacknowledgment.
DefinedErrorddetectiondanddcorrection.dE C925.1 2
rrordDetection:
Datadcandbedcorrupteddduringdtransmission.dItdisdcalleddasdanderror.dFordreliab
ledcommunication,dthedreceiverdmustdfinddoutdthederrorsdoccurreddin
, theddatadwhichdisd calleddasderrordetection.
ErrordCorrection:
Itdisd thedmechanismdtodcorrectdthederrorsdandditd cand bedhandleddind2d ways.
• Whendanderrordisddiscovered,dthedreceiverdcandhavedthedsenderdretransmitdthede
ntireddatadunit.
• Adreceiverdcandusedanderrordcorrectingdcoder,dwhichdautomaticallydcorrectsdc
ertainderror.
Whatdaredthedissuesdinddatadlinkdlayer? C925.1 2
Theddatadlinkdlayerdhasdadnumberdofdspecificdfunctionsditdcandcarrydout.dThesedfu
nctionsdinclude,
a) Providingdad well-definedd servicedinterfacedtod thednetworkdlayer.
b) Dealingdwithdtransmissiond errors.
c) Regulatingdthedflowdofddatadsodthatdslowdreceiversdarednotdswampeddbydfastds
enders.
Whatdaredthedwaysdtodaddressdthedframingdproblem? C925.1 2
Thedframingdproblemdcand bedaddressedd bydthed followingdprotocols:
• Byte-OrienteddProtocols(PPP)
• Bit-OrienteddProtocols(HDLC)
• Clock-Basedd Framing(SONET)
Whatdaredthedresponsibilitiesdofddatadlinkdlayer? C925.1 2
Specificdresponsibilitiesdofddatadlinkdlayerd included thedfollowing.
• Framing
• Physicaldaddressing
• Flowdcontrol
• Errordcontrol
• Accessdcontrol
Mentiondthedtypesdofderrors. C925.2 2
Theredared2dtypesdofderrors
a) Single-bitderror.
b) Burst-bitderror.
Singledbitderror:dThedtermdsingledbitderrordmeansdthatdonlydonedbitdofdadg
ivenddatadunitd(suchdasdbytecharacter/datadunitdordpacket)disdchangeddfro
md1dtod0dordfromd0dto1.
Burstd error:dMeansdthatd2dordmoredbitsd indtheddatadunitdhavedchangeddfromd1d tod0
fromd0dto1.
Whatdisdredundancy? C925.2 2
Itdisd thederrorddetectingdmechanism,dwhichdmeansdad shorterdgroupdofd bitsdor
extradbitsd maydbeappendeddatdtheddestinationdofd eachdunit.
WhatdisdOSI? C925.1 2
AdstandarddthatdspecifiesdadconceptualdmodeldcalleddOpendsystemsd Interconnection
dnetworkdinterfacedmodel,dwhichdbreaksdnetworkeddcommunicationsd d intod d seven
d d layers:d d Application,d d Presentation,d d Session,
Transport,d Network,d Datadlink,dPhysical.
Stated thed majord functionsd performedd byd thed presentationd layerd ofd thed ISOdOS C925.1 2
Idmodel.
Presentationdlayerdisdconcerneddwithdthedformatdofddatadexchangeddbetweend peers,
dfordexample,whetherdandintegerdisd16,d32,dord64dbitsdlongdanddwhetherdthedmostd sig
nificantd bitd isd transmittedd firstd ord last,d ord howd ad videod streamd is
formatted.
TECHNOLOGY
20EC925d–
INFORMATIONdSECUIRTYdQUESTIONdBANKddWITHdEVALU
ATIONdSCHEME
MODULEdI-PARTdA
Whatd ared thed threed criteriad necessaryd ford and effectived andd efficientd network?dT C925.1 2
hedmostdimportantdcriteriadaredperformance,dreliabilitydanddsecurity.dPerformancedofdth
ednetworkddependsdondnumberdofdusers,dtypedofdtransmissiondmedium,dthe
capabilitiesdofdthedconnecteddh/wd anddthed efficiencydofdtheds/w.dReliabilitydis
measureddbydfrequencydofdfailure,dthedtimeditdtakesdadlinkdtodrecoverdfromdthedfailuredan
ddthednetwork’sdrobustnessdindadcatastrophe.dSecuritydissuesdincludeprotectingddatadfro
mdunauthorizeddaccessdanddviruses.
GroupdthedOSIdlayersdbydfunction. C925.1 2
ThedsevendlayersdofdthedOSIdmodeldbelongingdtodthreedsubgroups.dNetworkdsupport
d layers:d ConsistingdofdPhysical,d datad linkd andd networkdlayersd andd theyddealdwithd
thedphysicaldaspectsdofdmovingdatadfromdoneddevicedtodanother.dUserdsupportd layer
s:d Consistsd ofd Session,d presentationd andd applicationd layersd anddtheyd allowd int
eroperabilityd amongd unrelatedd softwared systems.d Thed transport
layerdensuresd end-to-endd reliableddatad transmission
Whatdaredthedfeaturesdprovideddbydlayering? C925.1 2
• Itddecomposesdthedproblemdofdbuildingdadnetworkdintodmoredmanageabledc
omponents.dRatherdthandimplementingdadmonolithicdpiecedofdsoftwaredthatd
doesdeverythingd implementdseveraldlayers,deachdofdwhichdsolvesdonedpartdo
fdthedproblem.
• Itdprovidesdmoredmodularddesign.dTodadddsomednewdservice,ditdisdenoughdt
odmodifydthedfunctionalitydatdonedlayer,dreusingdthedfunctionsdprovided
atdalldthedotherdlayers.
Whatdaredthedtwodinterfacesdprovideddbydprotocols? C925.1 2
• Servicedinterface
• Peerdinterface
• Servicedinterface-
definesdthedoperationsdthatdlocaldobjectsdcandperformdondthedprotocol.
• Peerdinterface-
definesdthedformdanddmeaningdofdmessagesdexchangeddbet
weenprotocoldpeersdtodimplementdthe
communicationd service.
WhatdisdLAN? C925.1 2
AdLANdisdadcommondnameduseddtoddescribedadgroupdofddevicesdthatdsharedadgeographic
dlocation.LANdisdlimiteddtodsingledbuildingdordcampus.
WhatdisdflowdControl? C925.1 2
Flowd controld refersd tod ad setd ofd proceduresd usedd tod restrictd thed amountd ofd data.
Thedsenderdcand senddbeforedwaitingdfordacknowledgment.
DefinedErrorddetectiondanddcorrection.dE C925.1 2
rrordDetection:
Datadcandbedcorrupteddduringdtransmission.dItdisdcalleddasdanderror.dFordreliab
ledcommunication,dthedreceiverdmustdfinddoutdthederrorsdoccurreddin
, theddatadwhichdisd calleddasderrordetection.
ErrordCorrection:
Itdisd thedmechanismdtodcorrectdthederrorsdandditd cand bedhandleddind2d ways.
• Whendanderrordisddiscovered,dthedreceiverdcandhavedthedsenderdretransmitdthede
ntireddatadunit.
• Adreceiverdcandusedanderrordcorrectingdcoder,dwhichdautomaticallydcorrectsdc
ertainderror.
Whatdaredthedissuesdinddatadlinkdlayer? C925.1 2
Theddatadlinkdlayerdhasdadnumberdofdspecificdfunctionsditdcandcarrydout.dThesedfu
nctionsdinclude,
a) Providingdad well-definedd servicedinterfacedtod thednetworkdlayer.
b) Dealingdwithdtransmissiond errors.
c) Regulatingdthedflowdofddatadsodthatdslowdreceiversdarednotdswampeddbydfastds
enders.
Whatdaredthedwaysdtodaddressdthedframingdproblem? C925.1 2
Thedframingdproblemdcand bedaddressedd bydthed followingdprotocols:
• Byte-OrienteddProtocols(PPP)
• Bit-OrienteddProtocols(HDLC)
• Clock-Basedd Framing(SONET)
Whatdaredthedresponsibilitiesdofddatadlinkdlayer? C925.1 2
Specificdresponsibilitiesdofddatadlinkdlayerd included thedfollowing.
• Framing
• Physicaldaddressing
• Flowdcontrol
• Errordcontrol
• Accessdcontrol
Mentiondthedtypesdofderrors. C925.2 2
Theredared2dtypesdofderrors
a) Single-bitderror.
b) Burst-bitderror.
Singledbitderror:dThedtermdsingledbitderrordmeansdthatdonlydonedbitdofdadg
ivenddatadunitd(suchdasdbytecharacter/datadunitdordpacket)disdchangeddfro
md1dtod0dordfromd0dto1.
Burstd error:dMeansdthatd2dordmoredbitsd indtheddatadunitdhavedchangeddfromd1d tod0
fromd0dto1.
Whatdisdredundancy? C925.2 2
Itdisd thederrorddetectingdmechanism,dwhichdmeansdad shorterdgroupdofd bitsdor
extradbitsd maydbeappendeddatdtheddestinationdofd eachdunit.
WhatdisdOSI? C925.1 2
AdstandarddthatdspecifiesdadconceptualdmodeldcalleddOpendsystemsd Interconnection
dnetworkdinterfacedmodel,dwhichdbreaksdnetworkeddcommunicationsd d intod d seven
d d layers:d d Application,d d Presentation,d d Session,
Transport,d Network,d Datadlink,dPhysical.
Stated thed majord functionsd performedd byd thed presentationd layerd ofd thed ISOdOS C925.1 2
Idmodel.
Presentationdlayerdisdconcerneddwithdthedformatdofddatadexchangeddbetweend peers,
dfordexample,whetherdandintegerdisd16,d32,dord64dbitsdlongdanddwhetherdthedmostd sig
nificantd bitd isd transmittedd firstd ord last,d ord howd ad videod streamd is
formatted.
