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CN - Unit 5

The document discusses various application layer protocols, focusing on DNS for translating domain names into IP addresses and SMTP for email communication. It explains how DNS resolves domain names through a hierarchical structure and how SMTP facilitates email transfer between clients and servers. Additionally, it covers the roles of different agents in email delivery and the process of converting analog signals into digital formats for audio and video streaming.

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Esprit Lawrence
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54 views10 pages

CN - Unit 5

The document discusses various application layer protocols, focusing on DNS for translating domain names into IP addresses and SMTP for email communication. It explains how DNS resolves domain names through a hierarchical structure and how SMTP facilitates email transfer between clients and servers. Additionally, it covers the roles of different agents in email delivery and the process of converting analog signals into digital formats for audio and video streaming.

Uploaded by

Esprit Lawrence
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
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OF Website USES e TCE ToT. “IP address to domain name mapping reer Deakag ton) Application Layer Name-to - Address Resolution — Host Yequests DNs Name seaves 40 Yesolve domain hame. And the Name server setusns IP address Cowesponding to domain name to host sed to reques| a ee —_ Arawer #: IPaddvess Woaking: =DNS Wwooks bby executing database whose Work ts to store name of hosts which ate available on the ‘Intesnet —Top level domain veeyuest then DNs Yesolver sends request +o DNs Sewer 4p Fetch IP address ~when it doesn't contain pacticulay IP addvess with hostname , tt Foxwards vequestto anothes DNS Sexvey When IP address has awsived at Yesolver, + Completes the request Over Internet Rotocol - Hierarchical access 10 domain name : ' Reot domain {in ong edu com net |Top level 3 domain 1 9 level domain Co ac Wikipedia | en exomple Sub domain Most /resource name DNs databace organisation \Rook pale] 12 woot sexvere are there Sewers ig Host database like youlube, 4 to avoid single point fat lure Glande for Simple network aed” ement Protocol —Romework fos managing devices ©” Intesnet ~ Manoges multiple devices Provides set of fundamental Operation aes es of Manager 4 Agen! mile : Internet ate ace Ceonteol age) @ SNMP ais ae eet compere) SNMP manager fs host tha® 149 SNMP cient peoqiany ~ SNMP agent ka =souter / Slortch that SON SNMP sewers program. Conmpanetis rsNmP manage® — Used +o monttoy network — known os netwosk management Sastem (Ns). * SNMP agent Manager access Values stored jn database , Whereas agent maintain Info in database. = Software module tnc-talled on ‘managed device *Managetnent \ofosmaton Base Up MIB. 3 basic tdea *Manager SM, Agent “Forces agent 4D perfortn task *Wasn about unusual situaton Characteristics Used to monitor netwook — Detects any network Faults ~ Allows standard way of collecting info. —Hb is one of most Widely aced BQ featives of intesnet along tlh Web- — E-mail messages ave usually encoded % ASCII tert and uses Wnultfple protocol within TcP/ IP —fopulas protocol tor sencling email fe smTP 4 for seceivin So % Post office psotocol (pop). ‘on, IP, udp & eqp, temp, cp hake >Managerrent of sNMP bad on ~ Used to configuie remote devices EEE —System intesace, address translal- = System consists of sul systems * Uses agents ~allow people to Yectd \ send email * Message tranches agents Allow to move message From source to destination —aalled as mat! senvers — Ack of sending naw messages inl Matl eystem— taf! subrission 7 Mail boxes store ematl that fe YeceNed fos uses > Envelope encapsulate Messages The message tnside tt has 2 farts: Header Body TWAttex Yeading a message, the User can decide what to clo Witb Tt — tnescage désposition > Messages cent by uses must be placed ip standard format to be handled by mail servers Message fosmert Heacles Meaning To: Ematl address of Psimasy vecetprent Person who crectledd Message Can ke Used dentify path back to the Sercler Heades Meanin Sender Email addrec of lu Wide Wa (iran: actual cencer —Wwn ts defined as the collecton Received. Line added boy each of different websttes around the Lransfer agent along — World, containing diffeaent ‘nfo he woute Shared via local sesvers “Final detttesy can't be achievediifl Wh) ts a globally connected ‘t gona mailbox muct continue to be Hebsork Stored on mail cower ~ Web pages one linked together > Uses agent May Dol be connected Using hypealinks which are HTML 4d intesnel at troment formatted & referred 4o hypertext “Types of E-wot| “these ave units of Inteanet and Senne Accessed heough Hypertext ~ Browser — based TWansfes Protocol (47 P) —ISP- based Architecture ~ Suite-haced —Web consists wosdldwide connection | Advantoges OF documents or welo pages ~Fages can be vetsieved 4 viewed — Grsumes altnoct no resource < 7 Nery fast = Message can be eclited foswarded, distsilbuted Disodvantoge — Not Completely Yelialle — Not Vewy secure — Not efficient means of Hansfenving binowy files by Using browsers fun) Ses pages vu Pts Malt theead Tere Downloader — The below diagram indicates ~ how Web operat + Nf Pp eve le: si Ke a _ chance for Hypes Text Wanste Te Client-server architecture De ae i ee Protocol —when user request web pages, — _ enables transfer of dota [lw then Web lorowsed of system c\tent & sexves Yequect to sevver for info aan | it paovides standard between Wels ewer provide requested Sewvices tp pyowses back & Finally cewvice tc utilized by User Welb bowers & server +o establish communication =\b % cok of rules for tronsfewing web browser request to data fiom ore computer to ar wee nother ewe —vohen Web user opens web browser, web cower Ahe web P29 USer indirectly uses HTT. Components of Web i +Unifosm Resource Locator CURL) i Sewves os system for sesources On web 1 sjag HTTP connect }On + Hyper Text Nanster Protocol (HTTP) ~~ ia Crrection te epecifies communication of bsowser and sexves ° HypeeText Maxkup Language Cat): define steuctute, organisation Q Content of web page Features & WWW: bee’ Open sousce —Bistrtouted system HTTP request /re sponse me Hypertext \nformation systera _iiitP ts a request - Yes ponse = Dynamic protoc| , which Ineans that for every tequest sent by c\ent, ~~ —\nteractive 3 Ane sewves Yespords with Tesponse Ni Sian the bast flow of HTTP request- Sheaming acto Gna vile F Yecbonse cycle fe as follows: rn ; 2 * Cent cends an HTTP sequest Auctio compression - - ei aia ° nue * Serer processes the request Audio data requis to hand width GS * Sesvex cends an HITP tesponse _ on ie e Compaesston 40 reduce the St#! GS * Client processes the Yesponse of audio e Features sr remove redundancy c ~ Stateless Ah rermove details that huma? e ~ text based tend not to pesceive : ~ Client sexvev mode J Digital Video a ~Yequest response ~ Sampling the analoq signals ae Ad On the requirement ae as ~ Each carple fs an fmagqe e = oe independent = Qvantizing each sarnple ¢ paeieecnd Ye presenting an image as a0 & ee array of piclure element e ~ Security tach pixel & moicture of color g Disadvantage = \mage compression e lack of security Ar Exploit spatial tedundancy e —Pexform Jc clow fos lar *rexplott aspect. humans tend ommance ic clo ¥ ee e » dala tronsfer. ~ Common Image compession + @& fosmerds. e AToint Pictures Expert Group (TPE 4) e i AW Graphical Intechange Format | car) . Streaming Stored audio and video $ —— ~ Client —sesver system — Sewer stores audio & video Files Client tequect Files, play them 8 they download,and pesfosin Nek like functions (rewind, pause) Playing data at Vight time Seaver Aides -fhe data Into seqroents ~ labels each seqmnent with the timestamp or frame id > Sothe client Knows when to Play the data — voiding stawation at client > the data must arrive quickly enough > Othewwice client cannot keep Playfing 5 To cteate a digital image, we need to convest continuous Sensed data ‘nio digital fosm. This include a processes : Sampling * Quantigation Sampling digitizing co-ordinate Nalue BELLO VOUGUOdOOCCCCCCEEEETEE zation digiti zing amplitude lenage Sampling Te convest continuous image 6x14) tnto diqftal fon, We have to sanrple function fh both coordinates § amplitude Digital auclfo for of an audio sfqnal - analog (sine wave for) > QOHz- QokKtle audio frequency fange =) We Fiq: audio Wave fosm 0 sep > Converting analog into digital data .Methods lke sarpling, Quantisaton are used to igitize audio signal b) Saropling sine Wave aaetaeat iG Steps fh converting analagidata ov Signal into digital data ~Sarmpling athe analog siqnal > Sample at some fixed datrate — Each sample fs an asbitrary Yeal number ~— Quantizing each sample +> Found each sample to one of @ finite nurmbes of values — EKepresent each cample tn fixed number of bits ~ Application layer prolocol ~ Mechanism for exchanging emai} Messages between Servers ~ €ssential in email communication Process “he client who wants 40 snd the mail opens TCP connection to SMP cerver and-then cence tOat acxoss “the Connection — SMTP Server fe always -OF Vetering tode-As soon it Vatens , SMTP Process intiates connectio® through post 25. After then chent sends mail instantly > SMTP wodel % of a types *End-to-Enel method * Store -and-Forwarel method eo e eo e e a End-to-end model te uced 10 communtectte ble Aifferent organtsations Whereas store and fosmard melfiod ts Used \litn an orgarisation —o exchange mal using TEP, MTA ’s Used. “MTA maintains a queue of mail in case of unavatlabtlthy of tecever. MTA ce\tvars matt to the © Matlboxes R fnfo con later ba downloaded by user cee Figs SMTP made! < | avers demand —s| User [sient males MTA “i tes queue al Message J ' - : | Transfer Dgent he sumone repiles eal Je pak a6 ae all : ‘ | 7 user | Canta [pa fe Be a Re Agent \ fo ee Ne | ranslerhegnt Components : — Mail User Agent — Nail Sulemission Agent — Mail sransfer Agent —Mail deltvey Agent Woxxing INCOMING, x | crarp Link uyréo ner EMail — = | nrework 1 { ee, | a >| | \g3 Wasnt | > i ee a ? | NETHIORIC I | pecetvER | pop unk mncound ourGei NEMO ~The etnail client connects +o an SMTP sewer to send thessages — cient formats the ematl accor ng to SMTP Protocol ~ Evnail client ectablishes connection to SMTP sesvex using post 26 ~ Then email transferred from client +o SMTP “Hf tecipien't domain & different row Senders, ow7p Sexver forwads the email to Yecipient': domatns Mail server ~ Recipient's war | sewer receives Mat! (gumrp «0 is h agin: OFF ty Protocol like FOPS og IMAP Poy Yecipien+ to Veceive %

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