Appicalfon Layer & hare crc Several applicalfons th Abe application \ fon lever J the Tytemet model that follows stho Men | conver paradhigre The client Server progreuns Con pe Avicted into G)yCodegrees Those that can be telly uscd by tbo user, SUth as erect, and hose that Gupporl otlor agplicakion programs Te Pomesy Name Systerm CDN) ise Supporting pregrre thak iS used by huey programs. Namespace %& To be un aod qrous, Abe names outer qned AD wecines ynust be- corefemlyy Selecked from a Spate. woth Complete control over the binding between the names and DP ackdew Seengly, Names emusic be. unique, hecause the addresses ore. wang ees © fh namesp ate. thal naps each addres to can be organned ty @Q ways. a UMaue heme ) Flak Neme spate D) Meravelscah Nearne Spare. Vy Flat Neune Space tlarne iS asmgned to an addiess, And Ae nicharackerg udithoul any etrudiice, ts cigadvantage % \ \ Carte be tused Tn large System Such as dhe Trteme | ge.queence of becouse He must be Centra Controlled. x rerarche cat Name Space ® Each name iG madorp Ff geverd Parts. el pork 2 Nakue of tbo orqenitalton ond park = Name oh the erqanitation A part = Debnes Aepartments fy the ogarivation. Domain Name Space a domain nome Sprce. defined fh On at the top. Jo hae & {terarchi ca) name Space, neds Sn Abig , the names Oe was deci fovrerted — tree etructire. WM the rect e Tree Can Nove only og levels. Label e Label whic ta dying SAH A saantinum of 63 Characters he rok lebd eo Dull hing:52 Domain Name + Each node & the ‘tree Hrs 0 dorm amy name, N full dort, fe a Sequence Of Labels seperated by dott |. Demain nowe & Hames ate adeoerys yead fran the node “P Ap tke wout. ape lack label ig tho label of tue oot (null. fate Fok @ A Say G row \abal\ ate! Aoresin Netee = veda) doweiw, nome Saami Ta, ody | owas, same ) Fiqe Domosn Nerwes & \+bets. D addy Qudefed Dewetn Nene SP oa lobed 1S terminated by & reall String » tren ak as called why quasteed oes afin pene: % RowrRallyy Quoltfred Porwetin Name CPRBN) TP ce lahat TS nok toncin ed by a voll sheng then & iS cated feuliely quoted Aomnath, nownes oH sents Mem a node, bi doem't reach to te soot, « FQDN Domam x Ws a Subrree Of the camain name Space.“ Are name of Whe cormomin WS tke name ot the ext ae Hi Ake Aop of the Subtree. Doren, Dekabution Of Name Space % The SH fonnation Contosned th tha comash name space. must toe ttored. MH IS Mref Fceterke because responching to requasts Jrom alt over the word places & heey load on the Syttem, BR inode unreliadle because ON AeSture malas the. claka. Foaccaitib lo. eWierardhy Of seme Sewers Ake sclulfon % to Attvbute the Aafomedton “among M4 compubers Called Dus Sewers Ore way iS, dbvicle ko whole spate BID Many domams, based the Wreck level. Drs allows Ponahe are tv bE ivicted Further theo Slee clomaine — Suh comeing,a & BR a arpa serve A oe US Server / [Sek QR GQ zt Of | Srdacdu — bleeda frwe, Goro Uae — tr | Bone What @ Server 7S responsible for or has covthaity ener called “ame”. We Can Athne Bene OS & Cont qucns part OF ke entite ‘ree. Qe Sener makes a database called a TONE {Me and beeps all tke infermakion for every node uncer that domes. Sewer cavidss domain grep Sub-ctomain’ and dilagabes pak of % anlkerity to otter servers. Aone (S wade Of Astoiled, tnlornation Por the part of the Aomofn hak 16 noe Asleg ated & reference ty there pots shor are. Aslegaiad, Reat es j Root Senrose By rook server 1S Oo fewer Whore ne consis Of tthe wide tee. A root Serves Aoetne thre amy Inkormstonabout clomeint fut ddaqates tks cuthovity ty olka, «| Prin org B Seconchary Servers DNs Amines tte above @ lypes Servers. +A "paimary geprer™ tC a Sener thelr Mores 0 Ae abouwk the rene for which & Ham cudhowity A secondary server — 1S & Server tbo transhkers the Cornplite. toforrm alton about a ore from another server stores the fe. On de lotoh ait. * Painory Serer loads al infommatron Leon the fick, athe Setodary Server toads all Information from tke porary Cerver. talhen tha Cetonctary, dowdrloads thom walien for ls Pamary His Called 1 done brant ber! Dns Wh the Tsternet o DN TS a protocal thar Gn be used th Aihherent plokjorms. Ty the Fntemek, the comaly tame space it dincdsd into @ — aifprent Sections Wy genedte domcins Country domains B Tnverse domains. ) Genere Domains & Reese: | hott 7 . ‘x Astines yoqitered Oss. accor cling to thet genete » ApH cThe tree “Chola - peretous gach rode & The Tree clobines a clomerin, —_ =[Anka | eS oro Hatines G, atrocpate Comparer bh Busines | Kime cor) __Coqmercial SupNielon | [2p | Cooperative busin ess Organpearong |_edu Eduction’ eilakos ink Gatton dione) — Crgartradiont w\ | vetary gnoupe Bee Ne BR ere are | Pexcer Wane AX Non profit — Orgesackont BD Cousy Domerres The Com em ain 3) Bnvese Dormebin, Te chery to clo a __ al. etthaa. Chale aed \ Setion uses tig - Character Counhy ie Used AD tap an -addrore “tA Kame, abbcovsations, Seton Labels can be organived, or they can je mere wpediic — nabfonad ctesiqnadione, For Ea, Wher a eeror has reteved & requart froma Yak.ras a fe Ahab Centering liet 4 Aithough “he Server client aulhorived — chrents. onty ua BP ackdresrs Of lhe ested WP Hendle a pointer query, the Thy erse to the coma name space with the coed arpa, The second level 1S also ore pemed thoadde. The res o& the dowain Avfines IP domain to actdod firgt Lowel neoclo single node addkesees. The Cowert hak homdle the Inverse domain are also address rerarthical. Aig preang ‘be neti part of the ghould he ab vaqher (evel Aban a@ the gubnelid port, and the Subnebid park higher thon the hostid part Th this, wey, a senrer serving he whole site 1S aba Yhan the Servers Serving Be Part level eath Subnet, higher Level Root level 2 7 anna cup: Cares Ye ay adciestes ae CaP ang. Bee Pavey. aE in eee] onpa a yao Le’ Coury Tnwerge: Aken stilea a Resolulton 4 Haring, a name to an adcrese or an Adolregg toa Kame Bw called, newoe- adetress yosoludton. Resdver® Drs is Aesiqned asa client | server eapplicolfons A host Yrat needs to map an adctress lo a name OF cr Nome toon addrese calls q@ DNS Client Called a “resolver.” The etolver accesses the clogetk Ds Server with @ rapping request: TP he yesolver Sewer hag the information, RH Saksfres the resdluer', othervomse, Te ihe vefers the resplver ko other Servers or ates Other Sewers 4) provide athe. Sromaation: RdLor the reschver yetieves the roaeping, & amterpret¢ the yesponte to See Th AWa real resclutfon OF aH Crror, and Finally dekivers the retull to ks process Thal sequert.a AL . Mapping loenes Lo Addtrestes She! resolver qives 0 dernotiy Ap “the. Server ‘ond athe ter comer pending adaress, My the Cate, Whe Server Chetks the AeeNe Apmmoting or Ae Comntry dom ing Ay fined “the mtg FW ke cheno rame if form be ynene dom acy Rl, abe xetolver yoweues, a Alora ame 9uch asW chal. ater Phela edu’. The qnery fe ene by the refolue, the local domes gener for resolutton. TE the local Sey. Cane regolve the qtiery, ik either refers “the reeolver tv other Servers or akg Olher Servers ‘irettly. Mapping Addresses to lames gy A chent can send an IP adelrese toa server to be mapped to a doom heme. TO answer the queries, Ong uses the Ghverse clamatn. Sh the requet, SP address & reversed and -hwo lakes th_addr and, arpa are epened appended to create a domeity Acceptable by the Thence. danas Cetkon. Reuusive Reselukrorn es The resolver enpecke the sewer to Supply Ahe incl anowe, DP vhe Cenwer ke the cudhority Aor the com ath name, | the authority, FR Sends, qeny Ao ty another Serves. fe checks its clatabase ond retponcts, Df tte Server te nek the authority, tk Sends Ake reqtietts ty another geves. find walls for the responce. Tf the parent cg Uhen he getty S finaly resolvect, the response travels back unttl # Finalty reaches the Fequuecting Clank his called =“ -secursive sellin’Root Serves a in* S a ne Ds aot, ‘a 2 iho trdaed Chere Fig: Recaxsive Reccution rocqicun.com Treyetive — Resolubton g- TH pe eter cloestt ase Rora returgive answer, the srapping Can be dere iteratively. TL the ewes 1S aN authority for the moune, sends the answer Be Fe fo nok, & cote “the SP address Of the Server thar Tt Thinks Gn yadve We qpey: Mhe clrenk fe responsible Avy repeal- wing abe queny to Ais Be cond Sesver DP the nedky aclresed) Rewer can yesclve the Problem, Re answers the quey with the TP address Athex wise » ‘L retuams tne TP adets ase Of a ned Server to Whe Cierty plow, Cred mutt Tepcak Tes qpory ro the ftp address Of a pe Losvedse thitd Sesves, Tris prowss iS calted “thasakive resoludton” S | 3. RD Soyuay owt —— ha jie 4 . ——— Gy mreqra.com SSCashing y for a name that Eath time a Server recieves a arery nek th its domain, H needs to search ite clatahase Ay gerver FP adetrest. DNS hendber thig with a methanista cated catheing: When a Sewer asks for a raappthg from another Server and retieves ‘he response it Stores -thig frfornalin th BE Cathe memory before Sending te 40 the Cent. ; + Cathing Speeds up resolutton, bub tt can also be problematic = Ga Sener caches a reapptig doe long Mime, & mea Send. an outdated mapping: to the Ufert, TW Counter this & vethniques ore used, D Authorative Server adds thformalfon to the mapping calted| irme-to -ve Cray. XD Drs reqrdres Ahab eath Sorver! coop ol it. Countey foy eath mapping i Caches. * DNS mesSages DAS has © Hyper of weseaes Dd query 2) response. Beth types hawe Aha Seamer formate, Wo ory mestage Conssks of a Header anc qW9skien Yeceraa, the regponge 4 messag? Comticls Of a heacloy, Qustion vecords, angwern |\ | Yecords, awhoratfre vecords , and -addittenal records, VWeador a Bot query t respense messages have the Same header AJormer vofth Sore fields Set to ero fos the quay mes ene header 1S Io bytes, Header i a ——=j | Queston Secon | Kecesion Sek > | FPniwer SE Ken f P ulkoy alpdive Sedfon | Shen 8) Response e We Jclents Weedon Subffeld is usedl by che cent to raakth the responte, wRh the query. The cUvent uses q Akfferat Werkeficalkten Munber each time fr Sends Q qussy- © Hage gubferd PS a tollettion Of Qubfreldgs that defi. the type Y metgage, the type of answer required, the type Of Assixad resoludten erd G om. w The nog, qusstion records Subffeld Containg the no. of Que nes tH The qusitfon Sein of the me ssaagas The no. of anwoer records Mbbreldy conkams the no: Of ennder tees RH the ansoer se chon:seertton of o rede records « 2 The nor oF onthortad ive authovixaltye. records Th 4 gubseeta contomng the no: of abe authoretive gectfon: : © the additional records fe gubPeeld conbahe the no. of | jhe addiirrora gettin Of « tices actetlefond re cords “in response ™m excage Btnertten Gad Fony Ta entopecodten Flags nlo-of answer nocords Ho of gestion records noo additonal qacords| | cloof awhoradtve records Questfon Sedfon a consietiig of cre or mere question retords | ey beth query ‘, wyegponte mesiages tm is nen A\naoer Secon ay Consisting OL one or mere pe source retord s os enly 6 respente. messages AY qneludes answer fren the \ | | Sesver ko the Ser Prthoratafve SertPens Sishing of one OF mere Tesoure roterds+ Ne {preset Oe AS presente TD con only ch yexponte mess ages, Gnformalfen Sectong Aaditfonal mk consih ng of one OF moe TeSDurce wenn, Set preset only Gon response Mesa ges.K psovides additiond Thfosrnalton. Types of Records % D Question Retord Me se used by Ufent to gr Ae rformadtion Sram a serves THIS Contains domain nome, 2 Regouree Record Bath domah name $8 assotraled wfth aretord Called Ake yesourte record: Me Serves database Comtrsts of resourte record. Reg FakroxS g ig clone throug, flow ore New dename added to PNeq Thr register, A Comm ap the) entity actrecdited boy Icann. \ regekror vestgees That clomofh name fs uneque and dhen enters & fo the DNS dababate. fckpt [| vowe. thinenic: nee Dynemie Demoin Nome Sytem CDD EN), Tr PSA, when a bincting bekoeen a name ancl on citermfneds the thhomahtn Fg Sent, usually. acdress 1S by, DROP Ted poimory Seaver upclaiad the Ione, The gerondary epvess are Hott fed cpttos Ad vely oF Passively Th goowids Se tuuity prevent — unauthowred changes f& the DS records, DNS Can Use an audhentt codf m methanism.Encapsul abton = Die Gn use ether TeR os ODP, Jn bold cates tha tod\ Venom pork used by The Server i$ pork SS ODP 1S Used then The Gre of the rekponse mes& and the Vine Re ail was gent OF neveved.dcresses & ; Nee avg Jo cleiver moe, oe mail hanclting syrtien rusk WSE an adele j syptten softh unique addresses, Aetclress consis of 10 . puts + sat ah a) Local part DF Aomah namo, opercted by om @ sign. | lol pat | © Domain Rare | dae ee BY Whe mailken Toran banne Of te Gr WW nil Conver mol cesvew. | Local Rotts Defines the name af a specs) fle, Called the | ger meiitbou, ehere all the mail redeved fox a User 16 Srred Fur retvieval by The message accel urgent Domain mares Po exgant tation LelUIS One oF inane hoses to redeve & sench pernats the. hosts are Sometimes Called mail Servers or t anthangerss De. Aoinath name assigned ty each mail exchan. — ger either comet from tue DNS database or ts a logical name. = Praiieng, Vekea tunes elultiperpose Anlemet Mail Extentions. Te 1a Cuppemenrany pmilveol thet allot none AgaT ctota to be Sent rrug e-mail ‘ © PE Aransforms none NSC Data at We sender Ge Ap VP Ace dete, Bb chekwers Them to theo Herk Mt do be Sent “Uheogh Ne Tyteanst. : = Tw message ok veitever Side iS tranthowmed Pack tothe one eat dala. nk+_ - == Messa§e transtes Agent 3 smirP- the aclual mori transtes f& done through message tranctes em us have the cltenl the Jormal protocol agenty to send matt a Syst maray and to sesves MIN. Recerve marl, A System must have 0 that defmes the MTA clvenk and serves th he Jatewnel cailed gitnple mat tronstes protocol (oth): © As we Satd before ttoo pars of Min c\ront [cesves programs oie used m the most Common sAluation - cme | arp cendet| | fae dl Pecaive : iL aN. AE as ———EE S , < 7 Len oY ant onvoon! s L J ae a #4 lnotl sewer marl sewer n dhe Sendes and the sender's © sump t% used co lanes , betwee matt genes and between the tivo man servers - AS We Lom See shortly» anothes protocol & needed between -the marl Server andl nthe Recerver. + SMP Umply detmes horw commands and Responses must be sent back and -Lonh -* gach network & free to choose a software package it finplementatton « Commands and Response + © gmTe Uses commands and Responses ~to thangtes messages beltaces an gTA- cirent and an MA sever. Common * Zach command of Reply fs -lermmated by a 4wo- character « end -of - hme token. Commands + & commands are seat from the clrent -fo she eerver «the fourat of a Keytuord s avquenent (5) j cornmand -lumat ceenmand *S t © Ak conetete of a keyword -farowed by dere 01 mone avgqumenly, © gitp defenes IH Commands. the fost Ave are mandatory 3 very tmplementatfon must support these de commands «the nent three | ane ollen ved and htyhly Recommended» the Bast gen are Seldom Used . [ Keyword Aiqument¢s) HELLO Mine FROM sender’ hast name of the message Rept 10 talended Recrpronk of tho message ; a533 Keyvoofds “Arqunent-c5) |_dern | eoty of the mon | ast | =e L_vrey “Nome of kar pent tobe verbal Nop | Lwet | = |__expn matting lest fo be enpanded KELP = Command name | SEND FROM fobended eecepreat of the 1 Message os SMoL FRom folended Reurprent of -the Mesage | SMAL FROM falended Receppent of the nesaye A Responses + * Responses Are sent ioen jhe sewes +o Ahe clvork. A Response ks a Aniee deqek code thot may be torowed by addettonal tentuat entotmation - come oh the Responses ARE et [ code / Descseptron oo ——————— —______Postive complettos Reply. _ an Sateen SHS OF np Realy 914 - _ Herp_message | 220 Seovece Ready | 22 Sewvee choseng hansntcston Channed. + | 250° Request command completed . _——_— apo® Code _ _Desurpton, ——— “ postieve completion Reply. “user not locals she message ott be forwarded. aon — Poseleve antermedvale Repty. au. — [stant mart dnput | ual | seweee nok _ OVaPlable 450 Maribor not © avarlable _fommand aboited Ss doce tuo Command Obotted : dnautecrenk b stosafle Permanent Hegalnve Completion) Repiy. | bmvecognraed Lommond | _| Sunten en Snort fn Parameters ot © axqumenty. = command nok _toplemented Badd sequence of commands, | command Aempoiarey not compete _ Admplenented | Command ° not eneuled s smarlbon cnavarlable _Wsernok Locad |_ Requested deckfon aborted s enceeded Storage locaton | “| Requested actron not daken; Marien nome not attowed | Nansaction -(aeded, “Ae the atte shows; Responses are dtveded nto fours caleqoney the Lettmost det of the code (2/3, U,and 5). detones the Category5-ly Mat transter phases « the proces of transtarmg a marl message o«urs fh three phaser; * connecton &slablechment, « marttranster, ond * Connection dermenation. Message Aeess Agent: Pop and Smar- w-tne task and she Second atages of tar! devery ase smtp’ nok myolved inthe sthrd stage because amtTp ® @ Nooetes smmp push protocol 5 Jt pushes the mescage from he etvent 40 the Server. 2 aw Othe Loords , he drvecton od the bulk data (mescaqes) &s hon the clvent 40 the Sewer. On ather hand» the thie stage needs a pull protocol; the clvent must pul messages-fiom -he sewes. acthe ditecttoa of the bulk dala Fs diom he seiVer +p -the clenk she thad ghage Uses a meseage acces Agent. qe Ace protocols ove avarable ; + cariently too mena and gniemek ryar} acces sPost offrce protocol » Verston 2 (pops) protocol, Yerston u Came pu)« = FoPs-- Posk obfce protsol, Vexston 3 (Pops): mae emvled tn funchonalsy » she clrent Pops Ts cangle and 4 ihe Receprent Computer ; the fesver por oftware % inlatted On eodtvouge dnvlatied On the marl sever.w~ YT — * ada acces shat Wweth the cient Vahen Ane User needs to 4,, yo B-tnarl fom the mariboa On -the mari sesver. pe s the cleenk Opens & Connectron slo Ahe sewer On icp pork lo. w + Ak then cends te oder name ond patsucord to access the maflben. x the uses can Ahen Qe and Reeve the mati messager, One by One gS afte |-sme —___ sre Geet Sended ——— | tmMAPu “Bob Rorertoy ZS \ Aostoroan S -—_ I nod serves [he Gene foe | PP2 has 2 modes: rhe delete mode and Keep mode. dn-the delete 7% de! oy wornl mode sAhe marl ¢s deleted from the maiibon -otley each eehreval, + Sa he Keep mod @) the mati Bemarns fr Ihe marlton alles Relerval. the delete mode ts nomratiy Used when the Uses ts Workvag a4 hes permanent computer and can Save and Osqanrae she Recewed mati Aer Readenq om Replymng. «the keep mode Fs normmauy Used then the sen acteers her earl Cuong fiom hes prvencoy compule, «the marl ¢s Read bul Kept en the system -for Later yelwteval and antaing «(emapu). IMAP fs srenflan Fe POPs, BAS “Ima pu’ Another mart access probxcol ts Aniermek matt Acces protocol Newton 4 but te has move teatures ; TNapa ty mare powerlul and more complen: the enchanSe ot commands and Responses ™ pops. Sater ve: pe. Bob's computer | serves pops Clrent Pops te dedvevent th Several hays dt doesnot autora the vse* +o | | Brqonvae ber marl On athe sesVes ¢ the User Cannot have det ferent Hades on the Sever’ syvapy provedes the fottoweng entra dunetions t Pu q | cr can check the emaed header prox to daontoad md. o AA 09 hh ahe content of the &-mard for a specefee shenQ | © Noses Can Seate oh characters pert to dovontond vag, | || | |getes ave stokmati and Yahoo: ~ = A aser can pavttally dovnload €- marl + thre Po kepecratly usedat il 7 Landurdth % temeted and the &- marl contams mulle medea wtth hry, bandwrdth Reguérements. ® HK user can chealey delete Of Rename manbones On -the. earl Sesves "AN ves can Greale a hrevarchy of martbones tm O Storage. web-based Maly AN RA AR © h a common applecatton that Some webseles today woo Common B-matt &% suc piovede thes Sere 4o Gnyone twho Accesses the 6Ale + oy) to hi she edea es Very avmple + mart suanstey fiom aAlece fs, brexsen to hes mari geaves & done Ahwough MTP + © sendeng craet eaves to the she thanstes of the mecsage hom 4h Recorweeg mae SeeVes & SA Through gmtP. Taran, the messoge tron athe eecerving server 4p Bob's browses &% done through 4 TP. The Sask Phase f& very fterestmg «Instead of pops or TmaPHs tere ee Normany used .vohen Bob needs to Rebreve hes e-marls, he gends O message 4o -Ihe coebsele- ste voebsele sends a dorm -to be felled en by Gob» tehrth Meludes -the teqvn nome and Ahe Passvoord. d4 the loq-" Name ond password march the emart ®% transtened Bioen the webs Server to Bobls browser fh HIML format . ye re Aoiden for &-sratl at o f