CS6250/l CSl 6250l Examl 1l (Latestl 2025/l 2026l Update)l Reviewl Q/Al |l Gradel A|l 100%l Correctl (Verifiedl Answers)
Q:l Whatl arel thel ramificationsl ofl thel hourglassl shapel ofl thel internet?
Answer:
IPv4,l TCP,l andl UDPl providel al stablel frameworkl throughl whichl therel isl anl ever- expandingl setl ofl protocolsl atl thel lowerl layersl (physicall andl data-linkl layers),l asl welll asl newl applicationsl andl servicesl atl thel higherl layers.l Butl atl thel samel time,l thesel samel protocolsl havel beenl difficultl tol replacel orl evenl modifyl significantly.l TCP/UDPl havel al lotl ofl productsl thatl dependl onl them.l Thisl actsl asl al shieldl forl IPv4l whichl hasl TCPl andl UDPl asl products
Q:l Repeaters,l hubs,l bridges,l routersl operatel onl whichl layers?
Answer:
Repeatersl -l Layerl 1l (Physical) Hubsl -l Layerl 1l (Physical) Bridgesl -l Layerl 2l (Datal link) Routersl -l Layerl 3l (Network)
Q:l Whatl isl al bridge,l andl howl doesl itl "learn"?
Answer:
Al bridgel isl al Layer2l devicel whichl forwardsl framesl tol thel nextl node.l Whenl al bridgel firstl receivesl al message,l itl sendsl itl tol alll linksl tol learnl whichl arel correct.l Thesel learnedl valuesl arel storedl inl al forwardingl table.Thel bridgel consultsl thel forwardingl tablel sol thatl itl onlyl forwardsl framesl onl specificl ports,l ratherl thanl overl alll ports.
Q:l Whatl isl al distributedl algorithm? 1 / 4
Answer:
Anl algorithml thatl runsl overl manyl systemsl atl thel samel time.Wikipedia:l "Distributedl algorithmsl arel al sub-typel ofl parallell algorithm,l typicallyl executedl concurrently,l withl separatel partsl ofl thel algorithml beingl runl simultaneouslyl onl independentl processors,l andl havingl limitedl informationl aboutl whatl thel otherl partsl ofl thel algorithml arel doing."
Q:l Explainl thel Spanningl Treel Algorithm.
Answer:
Findl thel shortestl pathl tol thel rootl forl eachl nodel inl al graph.l Inl thel initiation,l eachl nodel tellsl alll otherl nodesl thatl itl isl thel root.l Eachl nodel takesl alll messagesl froml surroundingl nodesl andl decidesl thel rootl andl thel pathl tol rootl basedl on: Nodel IDl -l Thel rootl ofl thel configurationl hasl al smallerl ID Distancel tol rootl nodel ifl thel rootsl havel equall IDs Bothl rootsl IDsl arel thel samel andl thel distancesl arel thel same,l thenl thel nodel breaksl thel tiel byl selectingl thel configurationl ofl thel sendingl nodel thatl hasl withl thel smallestl ID Inl addition,l al nodel stopsl sendingl configurationl messagesl overl al linkl (port),l whenl thel nodel receivesl al configurationl messagel thatl indicatesl thatl itl isl notl thel root,l e.g.l whenl itl receivesl al configurationl messagel froml al neighborl that:l a)l eitherl closerl tol thel root,l orl b)l itl hasl thel samel distancel froml thel root,l butl itl hasl al smallerl ID.
Q:l Whatl isl thel purposel ofl thel Spanningl Treel Algorithm?
Answer:
Tol removel loopsl froml al graphl andl providel thel shortestl pathl froml eachl nodel tol thel rootl node.l Removingl loopsl preventsl broadcastl storms
Q:l Whatl doesl thel transportl layerl provide?
Answer:
Thel transportl layerl providesl anl end-to-endl connectionl betweenl twol applicationsl thatl arel runningl onl differentl hostsl (onl thel samel orl differentl networks).
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Q:l Whatl Isl al packetl forl thel transportl layerl called?
Answer:
Segment
Q:l Whatl arel thel twol mainl protocolsl withinl thel transportl layer?
Answer:
Userl datagraml protocoll (UDP) Transmissionl Controll Protocoll (TCP)
Q:l Whatl isl multiplexing,l andl whyl isl itl necessary?
Answer:
Thel sendingl hostl willl needl tol gatherl datal froml differentl applicationsl (throughl differentl ports),l andl encapsulatel eachl datal chunkl withl headerl informationl (thatl willl laterl bel usedl inl demultiplexing)l tol createl segments,l andl thenl forwardl thel segmentsl tol thel networkl layer.l Wel referl tol thisl jobl asl multiplexing Multiplexingl isl thel functionalityl byl whichl multiplel applicationsl inl thel samel hostl canl usel thel networkl simultaneously.l Itl isl providedl byl thel transportl layer.Multiplexingl isl neededl tol routel thel trafficl comingl intol thel hostl tol thel correctl applicationl (vial sockets).Multiplexingl usesl socketsl (transportl protocol,l IPl address,l port)l tol identifyl whichl applicationl (onl thel locall host)l isl listeningl tol whichl remotel application.
Q:l Whenl wouldl anl applicationl layerl protocoll choosel UDPl overl TCP?
Answer:
UDP Highestl throughput,l morel controll whenl sendingl data,l forl applicationsl morel sensitivel tol delays,l butl canl handlel datal loss.Ex.l Appl layerl protocols:l NFS,l SNMP,l RIP,l DNS,l streamingl data,l internetl telephony TCP Deliveryl guarantee Ex.l Appl layerl protocols:l SMTP,l HTTP,l FTP,l streamingl data,l internetl telephony 3 / 4
Q:l Describel thel twol typesl ofl multiplexing/demultiplexing.
Answer:
Al socketl isl onel endpointl (IPl addressl &l port)l ofl al two-wayl communicationl linkl betweenl twol programsl runningl onl thel network.l Al socketl isl boundl tol al portl numberl sol thatl thel TCPl layerl canl identifyl thel applicationl thatl datal isl destinedl tol bel sentl to.
Connectionlessl (UDP):
Thel identifierl ofl al UDPl socketl isl al two-tuplel thatl consistsl ofl al destinationl IPl addressl andl al destinationl portl number.Thel UDPl headersl ofl al transport-layerl segmentl includel thel sourcel portl andl thel destinationl portl (Nol IPl address,l thatl isl usedl inl thel networkl layer).Whenl multiplexing,l al senderl hostl takesl al messagel froml thel applicationl layer,l appendsl thel UDPl headersl (sourcel portl &l destinationl port)l tol forml al segmentl andl forwardsl itl tol thel networkl layer.l Thisl isl encapsulation.Whenl demultiplexing,l thel transportl layerl atl thel receivingl hostl identifiesl thel correctl socketl byl lookingl atl thel destinationl portl inl thel incomingl segment.Note:l thel hostl willl forwardl thel segmentsl tol thel samel destinationl processl vial thel samel destinationl socket,l evenl ifl thel segmentsl arel comingl froml differentl sourcel hostsl and/orl differentl sourcel portl numbers
Connectionl orientedl (TCP):
Thel identifierl ofl al TCPl socketl isl al four-tuplel thatl consistsl ofl thel sourcel IPl addressl andl portl number,l andl thel destinationl IPl addressl andl portl number.Thel TCPl headersl ofl al transport-layerl segmentl includel thel sourcel portl andl thel destinationl portl (Nol IPl address,l thatl isl usedl inl thel networkl layer),l andl otherl bitsl (likel al speciall connection-establishmentl bit).Al connectionl isl firstl establishedl beforel clientl &l serverl exchangel data.
Q:l Whatl arel thel differencesl betweenl UDPl andl TCP?
Answer:
UDP Connectionlessl (nol threel wayl handshake), Unreliablel (Bestl effort,l nol deliveryl guarantee,l nol congestionl control).l Providesl veryl basicl functionalityl andl reliesl onl thel application-layerl tol implementl thel remaining.Offersl lessl delaysl andl betterl controll overl sendingl data.Nol congestionl controll orl similarl mechanisms
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