BT Nhóm

Bi tp nhmMn hc: Internet v thng mai in t Sinh vin thc hin ( Lp: CQ49/18.01)1. L Th Vn Anh2. Nguyn Th Huyn Chang3. Hong Ngc Dung4. Lu Tin t5. Phm Th Thy H6. Nguyn Th Hin7. Nguyn Th Thu Hin8. Hong Th Hu9. Phan Quang Tun Hong10. Nguyn Th Thanh Huyn (A)11. Nguyn Th Thanh Huyn (B)12. Hu Hng13. Trn Mnh Hng14. H Th Thanh Hng

CHNG I: INTERNET V CC DCH VCu 1. Phn loi mng my tnh v cho bit vai tr ca n i vi thng mi in t.1.1. Khi nim: Mng my tnh l mt nhm cc my tnh v thit b ngoi vi kt ni vi nhau thng qua cc phng tin truyn dn ( cp, sng in t, tia hng ngoi) chia s d liu cho nhau. D liu truyn t my ny sang my khc l cc bit nh phn 0 v 11.2. Phn loi mng my tnh:1.2.1. Theo quy m v khong cch a l: Trong cch phn loi ny ngi ta ch n i lng ng knh mng ch khong cch ca hai my tnh xa nht trong mng. Da vo i lng ny ngi ta c th phn mng thnh cc loi sau:ng knh mngV tr ca cc my tnhLoi mng

1 mTrong mt mt vungMng khu vc c nhn

10 mTrong 1 phng

Mng cc b, gi tt l mng LAN (Local Area Network)

100 mTrong 1 ta nh

1 kmTrong mt khu vc

10 kmTrong mt thnh phMng th, gi tt l mng MAN (Metropolitan Area Network)

100 kmTrong mt quc giaMng din rng, gi tt l mng WAN (Wide Area Network)

1000 kmTrong mt chu lc

10000 kmC hnh tinh

* Mng cc b LAN (Local Area Network) - Khi nim: Mng LAN l mt nhm my tnh v cc thit b truyn thng mng c ni kt vi nhau trong mt khu vc nh nh mt ta nh cao c, khun vin trng i hc, khu gii tr - c im ca mng LAN: Bng thng ln, c kh nng chy cc ng dng trc tuyn nh xem phim, hi tho qua mng. Kch thc mng b gii hn bi cc thit b. Chi ph cc thit b mng tng i r. Qun tr n gin. * Mng th MAN (Metropolitan Area Network)- Mng MAN gn ging nh mng LAN nhng gii hn ca n l mt thnh ph hay mt quc gia. Mng MAN ni kt cc mng LAN li vi nhau thng qua cc phng tin truyn dn khc nhau (cp quang, cp ng, sng, ) v cc phng thc truyn thng khc nhau.- c im ca mng MAN : Bng thng mc trung bnh, phc v cc ng dng cp thnh ph hay quc gia nh chnh ph in t, thng mi in t, cc ng dng ca cc ngn hng, Do MAN ni kt nhiu LAN vi nhau nn phc tp cng tng ng thi cng tc qun tr s kh khn hn. Chi ph cc thit b mng MAN tng i t tin.* Mng din rng WAN (Wide Area Network) - Mng WAN bao ph vng a l rng ln c th l mt quc gia, mt lc a hay ton cu. Mng WAN thng l mng ca cc cng ty a quc gia hay ton cu, in hnh l mng Internet. Do phm vi rng ln ca mng WAN nn thng thng, mng WAN l tp hp cc mng LAN, WAN ni li vi nhau bng cc phng tin nh : v tinh (satellites), sng viba (microwave), cp quang, cp in thoi, - c im ca mng WAN : Bng thng thp, d kt ni, thng ch ph hp vi cc ng dng offline nh e-mail, web, ftp, .. Phm vi hot ng rng ln khng gii hn. Do kt ni ca nhiu LAN, MAN li vi nhau nn mng rt phc tp v c tnh ton cu nn thng l c t chc quc t ng ra qun tr. Chi ph cho cc thit b v cc cng ngh mng WAN rt t tin.* Mng ton cu GAN: l mt h thng thng tin ton cu c th c truy nhp cng cng gm cc mng my tnh c lin kt vi nhau. H thng ny truyn thng tin theo kiu ni chuyn gi d liu (packet switching) da trn mt giao thc lin mng c chun ha (giao thc IP). H thng ny bao gm hng ngn mng my tnh nh hn ca cc doanh nghip, ca cc vin nghin cu v cc trng i hc, ca ngi dng c nhn v cc chnh ph trn ton cu.

1.2.2. Theo kin trc mng* Mng trc tuyn tnh (Bus):Tt c cc trm phn chia mt ng truyn chung (bus). ng truyn chnh c gii hn hai u bng hai u ni c bit gi l terminator. Mi trm c ni vi trc chnh qua mt u ni ch T (T-connector) hoc mt thit b thu pht (transceiver). M hnh mng Bus hot ng theo cc lin kt Point to Multipoint hay Broadcast ( mt im - nhiu im ). u im: D thit k, chi ph thp. Khuyt im: Tnh n nh km, ch mt nt mng hng l ton b mng b ngng hot ng.Hin nay cc mng s dng hnh dng ng thng l mng Ethernet v G-net.* Mng hnh sao

Mng hnh sao c tt c cc trm c kt ni vi mt thit b trung tm c nhim v nhn tn hiu t cc trm v chuyn n trm ch. Tu theo yu cu truyn thng trn mng m thit b trung tm c th l Switch, router, hub hay my ch trung tm. Vai tr ca thit b trung tm l thit lp cc lin kt Point to Point (mt im - mt im) u im: Thit lp mng n gin, d dng cu hnh li mng (thm, bt cc trm), d dng kim sot v khc phc s c, tn dng c ti a tc truyn ca ng truyn vt l. Khuyt im: di ng truyn ni mt trm vi thit b trung tm b hn ch (trong vng 100m, vi cng ngh hin nay).Hin nay cc mng s dng hnh dng hnh sao l mng STARLAN ca AT&T v S-NET ca Novell.* Mng hnh vng (Ring)Trn mng hnh vng tn hiu c truyn i trn vng theo mt chiu duy nht. Mi trm ca mng c ni vi nhau qua mt b chuyn tip (repeater) c nhim v nhn tn hiu ri chuyn tip n trm k tip trn vng. Nh vy tn hiu c lu chuyn trn vng theo mt chui lin tip cc lin kt Point to Point gia cc repeater. Hin nay cc mng s dng hnh dng vng trn l mng Tocken ring ca IBM1.2.3. Phn loi theo chc nng: * M hnh ngang hng (Peer to Peer) Mng peertopeer l mt v d rt n gin ca cc mng LAN. Trong m hnh ny tt c cc my u bnh ng vi nhau, ngha l mi my va c th cung cp ti nguyn ca mnh cho cc my khc, va c th s dng ti nguyn ca cc my khc trong mng. M hnh ny ch ph hp vi cc t chc nh v khng quan tm n vn bo mt. Cc c im ca mng ngang hng l mng c bit n nh mng nhm lm vic v c s dng cho cc mng c 10 ngi s dng lm vic trn mng ; khng i hi phi c ngi qun tr mng u im: n gin cho vic ci t v chi ph tng i r. Nhc im: Khng qun tr tp trung, c bit trong trng hp c nhiu ti khon cho mt ngi s dng truy xut vo cc trm lm vic khc nhau; vic bo mt mng c th b vi phm vi cc ngi s dng c chung tn ngi dng, mt khu truy xut ti cng ti nguyn; khng th sao chp d phng d liu tp trung. D liu c lu tr ri rc trn tng trm * M hnh khch ch (Client - Server) My ch (Server ): l mng lin quan n vic xc nh vai tr ca cc thc th truyn thng trong mng. Mng ny xc nh thc th no c th to ra cc yu cu dch v v thc th no c th phc v cc yu cu . My tnh m bo vic phc v cc my khch bng cch iu khin vic phn b ti nguyn nm trong mng vi mc ch s dng chung. My khch (Client): l my s dng ti nguyn do my ch cung cp. Cc my c t chc thnh cc min (domain). An ninh trn cc domain c qun l bi mt s my ch c bit gi l domain controller. Trn domain c mt master domain controller c gi l PDC (Primary Domain Controller) v mt BDC (Backup Domain Controller) phng trng hp PDC gp s c.1.2.4. Phn loi mng my tnh theo k thut truyn tin* Mng qung b- Trong h thng mng qung b ch tn ti mt knh truyn c chia s cho tt c cc my tnh. - Khi mt my tnh gi tin, tt c cc my tnh cn li s nhn c tin .- Ti mt thi im ch cho php mt my tnh c php s dng ng truyn. * Mng im ni im - Trong h thng mng ny, cc my tnh c ni li vi nhau thnh tng cp. - Thng tin c gi i s c truyn trc tip t my gi n my nhn - Hoc c chuyn tip qua nhiu my trung gian trc khi n my tnh nhn2.5. Phn loi theo k thut chuyn mch*Chuyn mch knh: khi 2 my cn trao i thng tin vi nhau th gia chng s thit lp mt knh c nh v c duy tr cho n khi 1 trong 2 bn ngt lin lc. Cc d liu ch c truyn theo ng c nh . K thut chuyn mch knh c s dng trong cc kt ni ATM (Asynchronous Transfer Mode) v Dial-up ISDN (Integrated Services Digital Networks).V d v mng chuyn mch knh l mng in thoi- u im: Knh truyn c dnh ring trong sut qu trnh giao tip do tc truyn d liu c bo m. iu ny l c bit quan trng i vi cc ng dng thi gian thc nh audio v video- Nhc im: Mt thi gian thit lp knh c nh, hiu sut ng truyn khng cao, v c lc trn knh khng c d liu truyn ca hai trm kt ni, nhng cc trm khc khng c s dng knh truyn ny.* Chuyn mch thng bo: Khng ging chuyn mch knh, chuyn mch thng bo khng thit lp lin kt dnh ring gia hai trm giao tip m thay vo mi thng bo c xem nh mt khi c lp bao gm c a ch ngun v a ch ch. Mi thng bo s c truyn qua cc trm trong mng cho n khi n n c a ch ch, mi trm trung gian s nhn v lu tr thng bo cho n khi trm trung gian k tip sn sng nhn thng bo sau n chuyn tip thng bo n trm k tip, chnh v l do ny m mng chuyn mch thng bo cn c th c gi l mng lu v chuyn tip (Store and Forward Network). Mt v d in hnh v k thut ny l dch v th in t (e-mail), n c chuyn tip qua cc trm cho n khi ti c ch cn n.- u im: l cung cp mt s qun l hiu qu hn i vi s lu thng ca mng, bng cch gn cc th t u tin cho cc thng bo v m bo cc thng bo c u tin cao hn s c lu chuyn thay v b tr do qu trnh lu thng trn mng; gim s tc nghn trn mng, cc trm trung gian c th lu gi cc thng bo cho n khi knh truyn rnh mi gi thng bo i; tng hiu qu s dng knh truyn, vi k thut ny cc trm c th dng chung knh truyn.- Nhc im: l tr do vic lu tr v chuyn tip thng bo l khng ph hp vi cc ng dng thi gian thc, Cc trm trung gian phi c dung lng b nh rt ln lu gi cc thng bo trc khi chuyn tip n ti mt trm trung gian khc (kch thc ca cc thn bo khng b hn ch)* Chuyn mch gi: K thut ny c a ra nhm tn dng cc u im v khc phc nhng nhc im ca hai k thut trn, i vi k thut ny cc thng bo c chia thnh cc gi tin (packet) c kch thc thay i, mi gi tin bao gm d liu, a ch ngun, a ch ch v cc thng tin v a ch cc trm trung gian. Cc gi tin ring bit khng phi lun lun i theo mt con ng duy nht, iu ny c gi l chn ng c lp (independent routing).u im: l di thng c th c qun l bng cch chia nh d liu vo cc ng khc nhau trong trng hp knh truyn bn; nu mt lin kt b s c trong qu trnh truyn thng th cc gi tin cn li c th c gi i theo cc con ng khc; im khc nhau c bn gia k thut chuyn mch thng bo v k thut chuyn mch gi l trong k thut chuyn mch gi cc gi tin c gii hn v di ti a iu ny cho php cc trm chuyn mch c th lu gi cc gi tin vo b nh trong m khng phi a ra b nh ngoi do gim c thi gian truy nhp v tng hiu qu truyn tin.Nhc im: l kh khn ca phng php chuyn mch gi cn gii quyt l tp hp cc gi tin ti ni nhn to li thng bo ban u cng nh x l vic mt cc gi tin.1.3. VAI TR I VI THNG MI IN T:- Mng my tnh l tp hp cc my tnh c ni vi nhau bi ng truyn theo mt cu trc no , thng qua cc my tnh c th trao i thng tin qua li cho nhau- Vai tr ca mng my tnh Nhiu ngi c th dng chung mt phn mm tin ch. Mt nhm ngi cng thc hin mt n nu ni mng h s dng chung d liu ca n, dng chung tp tin chnh (master file) ca n, h trao i thng tin vi nhau d dng. D liu c qun l tp trung nn bo mt an ton, trao i gia nhng ngi s dng thun li, nhanh chng, backup d liu tt hn. S dng chung cc thit b my in, my scaner, a cng v cc thit b khc. Ngi s dng v trao i thng tin vi nhau d dng thng qua dch v th in t (Email), dch v Chat, dch v truyn file (FTP), dch v Web,... Xa b ro cn v khong cch a l gia cc my tnh trong h thng mng mun chia s v trao i d liu vi nhau. Mt s ngi s dng khng cn phi trang b my tnh t tin (chi ph thp m chc nng li mnh). Cho php ngi lp trnh mt trung tm my tnh ny c th s dng cc chng trnh tin ch, vng nh ca mt trung tm my tnh khc ang ri lm tng hiu qu kinh t ca h thng. An ton cho d liu v phn mm v n qun l quyn truy cp ca cc ti khon ngi dng (ph thuc vo cc chuyn gia qun tr mng). Vai tr quan trng nht ca mng my tnh i vi thng mi in t chnh l em li s tit kim chi ph v to thun li trong thng mi in t. Cc giao dch qua mng my tnh(Internet) c chi ph rt r, mt doanh nghip c th gi th tip th, cho hng n hng lot khch hng ch vi chi ph ging nh gi cho mt khch hng. Vi TMT, cc bn c th tin hnh giao dch khi cch xa nhau, gia thnh ph vi nng thn, t nc ny sang nc kia, hay ni cch khc l khng b gii hn bi khng gian a l. iu ny cho php cc doanh nghip tit kim chi ph i li, thi gian gp mt trong khi mua bn. Vi ngi tiu dng, h c th ngi ti nh t hng, mua sm nhiu loi hng ha, dch v tht nhanh chng.Cu 2. Cu trc ca mng internetInternet l mt lin mng, tc l mng ca cc mng con. kt ni hai mng con vi nhau, c hai vn cn gii quyt : Vn th nht: V mt vt l, hai mng con ch c th kt ni vi nhau khi c mt thit b c th kt ni vi c hai mng ny. Vic kt ni n thun v vt l cha th lm cho hai mng con c th trao i thng tin vi nhau.

Vn th hai: Thit b kt ni c v mt vt l vi hai mng con phi hiu c c hai giao thc truyn tin mc s dng trn hai mng con ny v cc gi thng tin ca hai mng con s c gi qua nhau thng qua thit b . Thit b ny c gi l cng ni Internet (Internet Gateway) hay B nh tuyn (Router). Hnh minh ha: Hai mng Net 1 v Net 2 kt ni thng qua Router R. Khi kt ni mng tr nn phc tp hn, cc Router cn phi bit v s kin trc ca cc mng kt ni. V d trong hnh sau y cho thy nhiu mng mc kt ni bng 2 Router.Hnh minh ha Mng kt ni vi nhau thng qua 2 router Nh vy, Router R1 phi chuyn tt c cc gi thng tin n mt my nm mng Net 2 hoc Net 3. Vi kch thc ln nh mng Internet, vic cc Router quyt nh chuyn cc gi thng tin cho cc my trong cc mng s tr nn phc tp hn. cc Router c th thc hin mc cng vic chuyn mt s ln cc gi thng tin thuc cc mng khc nhau, ngi ta ra quy tc l: cc Router chuyn cc gi thng tin da trn a ch mng ni n, ch khng phi da trn a ch ca my nhn. Nh vy, da trn a ch mng nn tng s thng tin m Router phi lu gi v s kin trc mng s tun theo s mng trn Internet ch khng phi l s my trn Internet. Trn Internet, tt c cc mng u c quyn bnh ng cho d chng c t chc hay s lng my c s khc nhau. B giao thc TCP/IP ca Internet hot ng tun theo quan im sau: tt cc cc mng con trong Internet nh l Ethernet, mt mng din rng nh NSFNET Backbone hay mt lin kt im-im gia hai my duy nht u mc coi nhm l mt mng. iu ny xut pht t quan im u tin khi thit k giao thc TCP/IP l c th lin kt gia cc mng c kin trc hon ton khc nhau. Khi nim "mng" i vi TCP/IP b n i phn kin trc vt l ca mng. y chnh l im gip cho TCP/IP tr ln rt mnh. Nh vy, ngi dng trong Internet hnh dung Internet l mt mng thng nht v bt k hai my no trn Internet u c ni vi nhau thng qua mt mng duy nht.

Hnh sau m t kin trc tng th ca Internet:(a) Mng Internet di con mt ngi s dng.Cc my c ni vi nhau thng qua mt mng duy nht

(b) Kin trc tng qut ca Mng internet

Cc Router cung cp cc kt ni gia cc mng.Cu 3: Trnh by v IP v h thng tn min 3.1. a ch IP:3.1.1. Khi nim:- Mi my trn mng TCP/IP hay cn gi l trm TCP/IP c nhn dng bng 1 a ch IP logic. Mi trm hay mi thit b mng s dng TCP/IP truyn thng cn c 1 a ch IP duy nht.- a ch IP cho bit v tr ca 1 h thng trong 1 mng ging nh a ch xc nh ngi nh trn 1 con ng no . Tng t nh 1 khu dn c. a ch IP phi l duy nht trn ton cu v phi c vit di 1 nh dng chun.3.1.2.Phng php nh a ch IP:- Mi a ch IP c chia thnh 2 phn : Phn a ch mng (Net ID) v Phn a ch trm (Host ID). + Net ID: Dng nhn dng nhng h thng trong cng 1 khu vc vt l cn c gi l Phn on (Segment). Mi h thng trong cng 1 Phn on phi c cng a Ch Mng v Phn a ch ny phi l duy nht trong s cc mng hin c.+ Host ID: Dng nhn dng 1 trm lm vic, 1 my ch, 1 Router hoc 1 trm TCP/IP trong 1 phn on. Phn a ch trm cng phi l duy nht trong 1 mng- Ging a ch bu in gm 2 phn: M BU IN S NH,TN NG. a ch IP cng gm 2 phn: NET ID HOST ID. + Phn u tin, NET ID nhn dng mng m my tnh ni ti, tt c my tnh trong cng mng phi c cng NET ID ging nh mi nh trong cng qun phi c cng M BU IN.+ Phn th hai, HOST ID xc nh my tnh, router hoc thit b mng khc trong mng. HOST ID phi l duy nht trong 1 mng ging nh S NH,TN NG phi l duy nht trong 1 qun. Hai my tnh c th c cng HOST ID nu NET ID ca chng khc nhau, ging nh hai NG c th cng tn nu nh chng thuc 2 qun khc nhau. - S kt hp gia NET ID v HOST ID phi cho php nhn dng duy nht mi my tnh ring bit. - Cc a ch IP c chiu di 32bit c chia thnh 4 dy. Mi dy gm 8bit (1Byte), mi Byte c phn cch = 1 du ., 1 Byte l 1 gi tr nm trong khong t 0-255. Cch biu din nh vy gi l K hiu thp phn du chm (Dotted-Decimal Notation) cho mi ngi s dng nh a ch 1 cch d dng.V d mt a ch IP ca my ch web ti VDC l 203.162.0.8.3.1.3. Lp a ch:- C 5 lp a ch IP to cc mng c kch thc khc nhau gm: Lp A, Lp B, Lp C, Lp D, Lp E. Trong , 3 lp u l c dng cho mc ch thng thng, cn hai lp D v E c dnh cho nhng mc ch c bit v tng lai.- TCP/IP h tr gn a ch lp A, lp B, lp C cho cc trm. - Cc lp ny c chiu di phn NET ID v HOST ID khc nhau nn s lng Mng v s lng Trm trn mi mng cng khc nhau: + Lp A: c gn cho cc Mng c kch thc cc ln. Trong lp a ch ny Byte u tin xc nh NET ID, Bit cao nht ca Byte ny lun c t l 0. 3 Byte cn li xc nh Host ID. Do lp A c th cp cho 126 Mng vi 16.777.214 Trm trn mi Mng.

31 30 24 23 00Network IDHost ID

Khun dng a ch IP lp A+ Lp B: c gn cho cc Mng c kch thc va v ln. Trong lp a ch ny 2 Byte u tin xc nh NET ID, 2 Bit cao nht ca Byte u tin lun c t l 1 0. 2 Byte cn li xc nh Host ID. Do lp B c th cp cho 16.384 Mng vi 65.534 Trm trn mi Mng. 31 30 29 16 15 010Network IDHost ID

Khun dng a ch IP lp B+ Lp C: c gn cho cc Mng c kch thc nh. Trong lp a ch ny 3 Byte u tin xc nh NET ID, 3 Bit cao nht ca Byte u tin lun c t l 1 1 0. Byte cui cng xc nh Host ID. Do lp C c th cp cho 2.097.152 Mng vi 254 Trm trn mi Mng. 31 30 29 28 8 7 0110Network IDHost ID

Khun dng a ch IP lp C+ Lp D: Cc a ch lp ny s dng cho Truyn a Hng (Multicast). + Lp E: L lp a ch thc nghim, n khng c thit k cho mc ch s dng chung. Lp E c d phng cho cc ng dng tng lai.

3.2. H thng tn min3.2.1. nh ngha tn min:Ngy nay, mng Internet c pht trin rng khp trn ton th gii. c th khai thc v s dng cc dch v v ng dng trn mng Internet chng ta cn phi xc nh c v tr ca mi my tnh.a ch Internet (IP) ang c s dng hin ti l th h a ch IPv4 c 32 bit chia thnh 4 Octet, mi Octet c 8 bit, tng ng vi 1 byte c m t tri qua phi t bit 1 n bit 32, cc Octet tch bit nhau bng du chm "." v biu hin dng thp phn y l 12 ch sV d mt a ch Internet: 203.119.8.101Hin nay mt s quc gia a vo s dng a ch IPv6 nhm m rng khng gian a ch v s dng nhng ng dng v tnh nng mi ca IPv6, a ch IPv6 gm 128 bit di gp 4 ln so vi di ca a ch IPv4. Ni cch khc chnh xc hn l a IPv4 c kh nng cung cp 232= 4 294 967 296 a ch, cn a ch IPv6 c kh nng cung cp ti 2128a ch.a ch dng ch s di nh vy rt kh nh, dn n vic s dng dch v do mt my tnh trn mng cung cp l rt kh, h thng DNS c sinh ra gn cho mi a ch IP dng s mt tn dng ch tng ng, d nh. Cc tn dng ch ny c gi l tn min. Cc tn min ny thng c ngha lin quan n cc dch v c cung cp.V d: My ch Web Server ca VNNIC c a ch l 203.119.8.101, tn min ca n lwww.vnnic.vnNgi s dng khng cn bit n a ch IP m ch cn nh tn min ny l truy cp c vo trang web ca VNNIC.Tn min l mt danh t dch theo kiu ngha ca tng t mt (word by word) t ting Anh (domain name). Thc cht tn min l s nhn dng v tr ca mt my tnh trn mng Internet ni cch khc tn min l tn ca cc mng li, tn ca cc my ch trn mng Internet. Mi a ch bng ch ny phi tng ng vi mt a ch IP dng s.

3.2.2. H thng tn min (DNS Domain name system):H thng tn min bao gm mt lot cc c s d liu cha a ch IP v cc tn min tng ng ca n. Mi tn min tng ng vi mt a ch bng s c th. H thng tn min trn mng Internet c nhim v chuyn i tn min sang a ch IP v ngc li t a ch IP sang tn min.Trong nhng ngy u tin ca mng Internet, tt c cc tn my v a ch IP tng ng ca chng c lu gi trong file hosts.txt, file ny c trung tm thng tin mng NIC ( Network Information Center ) M lu gi. Tuy nhin khi h thng Internet pht trin, vic lu gi thng tin trong mt file khng th p ng nhu cu phn phi v cp nht. Do , h thng tn min DNS pht trin di dng cc c s d liu phn b, mi c s d liu ny s qun l mt phn trong h thng tn min.

3.3.3. Cu trc ca h thng tn minHin nay h thng tn min trn th gii c phn b theo cu trc hnh cy. tn min cp cao nht l tn min gc (ROOT) c th hin bng du ".".Di tn min gc c hai loi tn min l: tn min cp cao dng chung- gTLDs (generic Top Level Domains) v tn min cp cao quc gia ccTLD (country code Top Level Domains) nh .vn, .jp, .kr, .

Cu trc ca h thng tn min

Hnh trn cc tn min iTLD v usTLD thc cht thuc nhm gTLD (vic phn tch ra ch c ngha lch s). Tn min cp cao dng chung hin nay c t chcquc t ICANN (Internet Coroperation for Assigned Names and Numbers) qun l. Cu trc h thng tn min quc gia .VN:Ti Vit Nam, tn min cp quc gia c ICANN phn b l ".VN" v nm trong nhm tn min cp cao quc gia ccTLD. Cu trc tn min quc gia Vit Nam ".VN" c quy nh trong Thng t s 09/2008/TT-BTTTT ngy 24/12/2008 ca B Thng tin v Truyn thng :1. Tn min .VN l tn min quc gia cp cao nht dnh cho Vit Nam. Cc tn min cp di .VN u c gi tr s dng nh nhau nh danh a ch Internet cho cc my ch ng k ti Vit Nam.2. Tn min cp 2 l tn min di .VN bao gm tn min cp 2 khng phn theo lnh vc v tn min cp 2 dng chung (gTLD) phn theo lnh vc nh sau:a) COM.VN: Dnh cho t chc, c nhn hot ng thng mi.b) BIZ.VN: Dnh cho cc t chc, c nhn hot ng kinh doanh, tng ng vi tn min COM.VN.c) EDU.VN: Dnh cho cc t chc, c nhn hot ng trong lnh vc gio dc, o to.d) GOV.VN: Dnh cho cc c quan, t chc nh nc trung ng v a phng.) NET.VN: Dnh cho cc t chc, c nhn hot ng trong lnh vc thit lp v cung cp cc dch v trn mng.e) ORG.VN: Dnh cho cc t chc hot ng trong lnh vc chnh tr, vn ho, x hi.f) INT.VN: Dnh cho cc t chc quc t ti Vit Nam.g) AC.VN: Dnh cho cc t chc, c nhn hot ng trong lnh vc nghin cu.h) PRO.VN: Dnh cho cc t chc, c nhn hot ng trong nhng lnh vc c tnh chuyn ngnh cao.i) INFO.VN: Dnh cho cc t chc, c nhn hot ng trong lnh vc sn xut, phn phi, cung cp thng tin.k) HEALTH.VN: Dnh cho cc t chc, c nhn hot ng trong lnh vc dc, y t.l) NAME.VN: Dnh cho tn ring ca c nhn tham gia hot ng Internet.m) Nhng tn min khc do B Thng tin v Truyn thng quy nh.3. Cc tn min cp 2 theo a gii hnh chnh l tn min Internet c t theo tn cc tnh, thnh ph trc thuc trung ng. Tn min cp 2 theo a gii hnh chnh c vit theo ting Vit hoc ting Vit khng du.4. Tn min ting Vita) Tn min ting Vit nm trong h thng tn min quc gia Vit Nam .VN trong cc k t to nn tn min l cc k t c quy nh trong bng m ting Vit theo tiu chun TCVN 6909:2001 v cc k t nm trong bng m m rng ca ting Vit theo tiu chun ni trn.b) Tn min ting Vit gm c tn min cp 2 v tn min cp 3 di tn min cp 2 theo a gii hnh chnh vit theo ting Vit. Tn min phi r ngha trong ngn ng ting Vit, khng vit tt ton b tn min.H thng tn min c sp xp theo cu trc phn cp. Mc trn cng c gi l ROOT v k hiu l ., T chc qun l h thng tn min trn th gii l The Internet Coroperation for Assigned Names and Numbers (ICANN). T chc ny qun l mc cao nht ca h thng tn min (mc ROOT) do n c quyn cp pht cc tn min di mc cao nht ny.

3.3.4. Qui tc t tn minTn min nn c t n gin v c tnh cht gi nh vi mc ich v phm vi hot ng ca t chc s hu tn min.Mi tn min c c ti a 63 k t bao gm c du ..Tn min c t bng cc k t (a-z A-Z 0-9) v k t -.Mt tn min y c chiu di khng vt qu 255 k t.

3.3.5. nh ngha my ch tn min (name server)My ch tn min (name server) l my ch cha c s d liu dng cho vic chuyn i gia tn min v a ch IP. Nh cch phn cp ca h thng tn min, tng ng vi mi cp v mi loi tn min c my ch tn min phc v tn min cp v loi tn min . My ch tn min mc ROOT s cha c s d liu qun l tn min mc top-level-domain. mc quc gia s c my ch tn min qun l domain mc quc gia.H thng DNS nh ngha hai kiu my ch tn min l my ch tn min chnh (primary name server) v my ch tn min ph (secondary name server). Primary name server l my ch tn min ly d liu cho cc zone ca n t cc file c sn trn my.Secondary name server l my ch tn min ly d liu cho cc zone ca n t mt my ch tn min primary khc. Khi my ch secondary khi ng n s kt ni n my ch primary ly d liu t my ny v cho cc zone m n qun l. Qu trnh ly d liu t my primary v my secondary c gi l zone transfer.

3.3.6. My ch tn min DNS ROOT serverMy ch tn min mc cao nht (ROOT name server) l my ch tn min cha cc thng tin tm kim cc my ch tn min lu tr (authority) cho cc tn min thuc mc cao nht (top-level-domain).My ch ROOT c th a ra cc truy vn (query) tm kim ti thiu l cc thng tin v a ch ca cc my ch tn min authority thuc lp top-level-domain cha tn min mun tm. Sau , cc my ch tn min mc top-level-domain c th cung cp cc thng tin v a ch ca my ch authority cho tn min mc second-level-domain cha tn min mun tm. Qu trnh tm kim tip tc cho n khi ch ra c my ch tn min authority cho tn min mun tm.Theo c ch hot ng trn my ch tn min ng vai tr quan trng trong vic tm kim mt tn min bt k trn khng gian tn min. Qu trnh tm kim tn min lun c bt u bng cc truy vn gi cho my ch ROOT, nu nh cc my ch tn min mc ROOT khng hot ng, qu trnh tm kim tn min s khng c thc hin. trnh iu ny khng xy ra, trn mng Internet hin ti c 13 h thng my ch tn min mc ROOT, cc my ch tn min ny ni chung v ngay trong cng mt h thng cng c t ti nhiu v tr khc nhau trn mng Internet

Cu 4: Trnh by v www, web, websiteWorld Wide Web (gi tt l Web hay WWW): l mng li ngun thng tin cho php khai thc thng qua mt s cng c, chng trnh hot ng dui cc giao thc mng. WWW l cng c, phng tin, hay ng hn l mt dch v ca Internet. Mt ti liu siu vn bn - c gi ph bin hn l mt trang web l mt tp tin c m ho c bit, s dng ngn ng nh du siu vn bn -HTML (HyperText Markup Languages). Khi c mt trang web, c th nhp chut vo mt t hay mt hnh nh c m ho nh mt lin kt siu vn bn v s lp tc chuyn ti mt v tr khc nm bn trong ti liu hoc ti mt trang Web khc. Trang th hai c th nm trn cng my tnh vi trang u, hoc c th nm bt k ni no trn Internet. Mt tp hp cc trang Web c lin quan c gi l WebSite. Mi WebSite c lu tr trn trn mt my phc v Web, vn l cc my ch Internet lu trhng ngn trang Web ring l. Vic sao chp mt trang ln mt Web Server c gi l ti (hoc np) ln (uploading) hay cng b ( publishing). Web cung cp thng tin rt a dng bao gm vn bn, hnh nh, m thanh, video. Hin nay, cc trang Web s dng phn phi tin tc, cc dch v gio dc, thng tin, danh mc sn phm, cng nhiu th khc. Cc trang Web tng tc cho php cc c gi tra cu c s d liu, t hng cc sn phm v cc thng tin, gi stin thanh ton bng th tn dng .. Web l mt phn ca Internet, l mt loi dch v i vi nhng ngui truy cp ti nguyn ca Internet. Di dy l mt hnh nh ca mt trang Web:

Mt Website l mt dy cc trang Web lin kt vi nhau v lin kt vi cc site khc. Cc trang web cha vn bn (text), ha, cc qung cao (banner) v i khi c video v audio. Trang ch (home page) La trang u tin khi np mt URL. Trang ch cha cc lin kt n vng ring trong website. Trang web (web page): cc trang web cha cc thng tin v c lin kt ttrang ch n. Website trong thng mi in t coi nh mt ca hng trc tuyn hay ca hng o. Website l mt Show-room trn mng Internet ni trng by v gii thiu thng tin, hnh nh v doanh nghip v sn phm hay dch v ca doanh nghip (hay gii thiu bt k thng tin no khc) cho mi ngi trn ton th gii truy cp bt klc no. mt website hot ng c cn phi c tn min (domain), lu tr (hosting) v ni dung (cc trang web hoc c s d liu thng tin). c im tin li ca website: thng tin d dng cp nht, thay i, khch hng c th xem thng tin ngay tc khc, bt k ni no, tit kim chi ph in n, gi bu in, fax, thng tin khng gii hn (ng ti thng tin khng hn ch, khng gii hn s trang, din tch bng in...) v khng gii hn phm vi a l. Nhng phn ni dung thit yu ca mt website: website thng c cc phn ni dung sau: -Trang ch: trang u tin hin ln khi ngi ta truy cp website . Trang ch l ni lit k cc lin kt n cc trang khc ca website. Trang ch thng dng trng by nhng thng tin mi nht m DN mun gii thiu u tin n ngi xem. -Trang lin h: trng by thng tin lin h vi doanh nghip v thng c mt form lin h ngi xem g cu hi ngay trn trang web ny. -Trang thng tin gii thiu v doanh nghip (About us): ngi xem khi xem website v mun tm hiu v nh cung cp, do o DN cn c mt trang gii thiu vmnh, nu ra nhng th mnh ca mnh so vi cc nh cung cp khc. -Trang gii thiu v sn phm hay dch v: gii thiu sn phm, dch v vi cc thng tin v hnh nh minh ha. -Trang hng dn hoc chnh sch: dng cung cp thng tin cho ngi xem trong trng hp h mun mua hay t hng, dch v. Thng tin trn trang ny shng dn h phi lm g, chnh sch ca doanh nghip nh th no v.v... Trang ny s gip doanh nghip tit kim nhiu cng sc tr li cc cu hi lm th no ca ngi xem v to cho ngi xem n tng tt v tnh chuyn nghip ca doanh nghip. Cc Website c u im:(a) Chi ph thp so vi cc n phm qung co thng thngInternet rt khc cc n phm qung co thng thng vi gi r, qung co ca bn c th truy cp trong mt thi gian di, ni dung c th thay i m khng cn phi yu cu mt ai lm iu cho bn (nu bn s dng mth thng qun l ni dung CMS) v bn c th c kh nng tip cn vi mt i tng rng ln hn.y khng phi l ni rng bn khng nn s dng cc hnh thc khc ca vic qung co. Tt c cc bn c th s dng n thu ht ngi truy cp vo trang web ca bn v tm hiu v cng ty ca bn. Ngoi ra website c kh nng m ra cch thc giao tip gia cc khch hng tim nng v mt ngi bn hng.(b) Th trng m rngInternet cho php cc doanh nghip bt c v tr a l no u c th b qua cc ro cn v tr nn d tip cn, t bt c quc gia no trn th gii ca mt khch hng tim nng c truy cp Internet cng c th bit n bn.(c) a dng ha Doanh thuMt trang web khng phi ch l mt phng tin truyn thng i din cho cng ty ca bn, n l mt hnh thc ca phng tin thng tin m t mi ngi c th thu c thng tin. Bn c th s dng phng tin truyn thng ny bn khng gian qung co cho cc doanh nghip khc.(d) Phc v 24/7 v 365 ngyKhi bn ng ca hng hoc ngh, website nh mt cng c hu ch cung cp thng tin mi ni mi lc. N t phc v khch hng ca bn nh mt nhn vin tn tm m khng ku ca g!(e)Thun tinN c thm rt nhiu thun li cho mt ngi nghin cu mt sn phm trn Internet hn l c c trong mt chic xe, li xe v tm mt ni no hoc yu cu mt ai c thng tin v mt sn phm.Cc khch hng tim nng c th truy cp vo trang web ca bn bt c khi no h mun mt cch ring t v thoi mi, khng c nhng cng thng tn ti trong th gii thc.(f) Thm gi tr gia tng v hi lngTrang web ca bn c th tng thm gi tr trong cc mt khc, bi c li khuyn, t vn v ni dung quan tm chung chung, bn c th cung cp cho khch hng. iu ny cng s gip khch hng nh bn tt hn.(g) Ci thin tin cyMt trang web s cho bn c hi thng bo cho cc khch hng tim nng v nhng g bn ang c v ti sao bn xng ng c h tin tng. Trong thc t, nhiu ngi s dng Internet nghin cu trc khi mua hng h c th xc nh cho mnh ci m h cn mua. Internet cng cho php cc khch hng ca bn lm tip th cho bn.(h) C hi tng trngMt trang web phc v nh mt ni tuyt vi gii thiu tim nng cho cc nh u t, hin th nhng g h c nu u t, nhng g t c v nhng g n c th t c trong tng lai.(i) D dnh nhn thng tin phn hiKhch hng c th nhanh chng v d dng a ra kin phn hi v sn phm ca bn v / hoc cc phng php tip cn th trng.(k) Nghin cu th trng gi rBn c th s dng cc tnh nng trn trang web ca bn nh l phiu thm d kin ngi truy cp, cc cuc iu tra trc tuyn v cc s liuthng k ca trang web ca bn tm hiu nhng g khch hng mun xc nh xem bn c th ci thin sn phm ca bn v cch thc kinh doanh ca bn.S liu thng k trang web hin th cho bn c bao nhiu lu lng truy cp trang web ca bn nhn c, lm th no ngi truy cp c vo trang web ca bn v u, ngi truy cp l t u. website hot ng, cn nhng g?Vicxy dng website, ni mt cch nm na, cng ging nh vic xy dng mt doanh nghip ngoi thc t. Khi thnh lp doanh nghip, bn cn phi ng k tn doanh nghip v tr s ca doanh nghip. Tng t nh vy, mt website hot ng c, bn cng cn phi c tn min (domain) v ni lu tr web (web hosting) cho website . Trong , tn min l yu t cc k quan trng m bn cn phi ch v n gn lin vi thng hiu hoc sn phm ca bn. Mc d bn c th cha kinh ph hay cha c k hoch lp mt trang web th cng nn dnh t thi gian cho vic chn la v ng k tn min cho tng lai pht trin doanh nghip ca bn.Quy trnh pht trin websitechun c m phng theo m hnh thc nuc, cc giai on ch cht c chia thnh cc cng an nh hn, cho php thc hin song song nhiu cng an. Cccng ty thit k websitethng theo mt qui trnh nh sau:- Ly thng tin yu cu v nghin cu tnh kh thi- Thit k giao din- Xy dng c s d liu v Lp trnh- Kim tra cht lng, nghim thu v bn giao

Cu 5. Nu mt s dch v internet 5.1. World Wide Web (WWW)-L dch v thng dng nht trn Internet. s dng dch v ny, ngi dng cn mt trnh duyt Web thng gi l browser. Nhng trnh duyt web thng dng nht hin nay l: Firefox(Mozilla), Internet explorer (ca Microsoft), Google chrome(Google), Cc cc- truy cp mt trang web, bn cn bit a ch ca trang web (URL- Uniform Resource Location) ca trang web . V d truy cp vo trang web ca cng ty Microsoft, g vo: http://www. microsoft.com/. - Trong mi trang web truy cp, c th thy c vn bn, hnh nh, m thanh c trang tr v trnh by ht sc p mt.Ngoi ra, cc siu lin kt c s dng di chuyn ti cc trang web khc. Do con tr chut thng thay i hnh dng ngang qua mt i tng cha hyperlink nn y l cch n gin nhn din chng.WWW gip ton th gii to c hi cho ngi dng truy cp n mt kho tin khng l vi hng triu triu trang web. Dch v ny s dng giao thc HTTP(Hypertext Transfer Protocol).5.2. Th in t- EmailEmail(Electronic Mail) l dch v trao i cc thng ip in t bng mng vin thng. Cc thng ip ny thng c m ha di dng vn bn ASCIIC th gi cc tp tin m thanh, hnh nh, cc tp tin chng trnh km theo email.Email l mt trong nhng dch v ban u ca Internet, c s dng rng ri, chim phn ln lu lng trn mng Internet.Giao thc thng dng gi, nhn email l: SMTP(Simple Mail Tranfer Protocol)/POP3(Post office protocol 3). s dng dch v email, cn c: a ch email. Mt a ch email thng c dng: name@domainname. (domainname: tn min) Tn ng nhp v mt khu truy cp vo hp th. iu ny m bo ch ngi dng mi c th c th ca chnh mnh.a ch email c qun l bi 1 mail server. Nh cung cp dch v email thng l cc ISP nh VNPT, FPT, Do tn min trong cc a ch mail thng c dng: abc.vnn.vn, def.fpt.vn. C rt nhiu webside trn Internet cung cp dch v email min ph. Thng dng nht l yahoo, Hotmail, Gmail

5.3. Truyn ti tp tin FTPDch v ny dng truyn ti cc file d liu gia cc host trn Internet. Cng c thc hin truyn file l chng trnh ftp, s dng mt giao thc ca Internet l giao thc FTP(File Tranfer Protocol). Cng vic ca giao thc ny l thc hin chuyn cc file t mt my tnh ny sang my tnh khc., khng ph thuc vo vn v tr a l hay mi trng h iu hnh ca hai my. Hai my ch cn c phn mm hiu c giao thc FTP. s dng dch v trc ht phi c mt ng k ngi dng my remote, c password tng ng. Vic ny lm gim s ngi c php truy cp v cp nhp cc file trn h thng t xa. phin lm vic FTP lm vic c, cn 2 phn mm1. ng dng FTP client chy trn my ngi dng, cho php gi cc lnh n FTP host.2. FTP server chy trn my ch t xa, dng x l cc lnh FTP, dng x l cc lnh FTP ca ngi dng v tng tc vi h thng File trn host m n ang chy.5.4. Tn gu, chatCho php ngi dng c th trao i trc tuyn vi nhau trn Internet. Cch thng dng nht l bng vn bn. Nu ng truyn tt c th ni chuyn tng t nh in thoi, nu my gn webcam thi c th nhn c hnh nh ca ngi ang tr chuyn.Hin nay nhiu trang web cng gn vi chc nng din n trao i tho lun, cc phng chat, tn gu.Cc chng trnh h tr chat thng dng hin nay: facebook, skype, ntagram.5.5. Lm vic t xa TelnetDch v ny cho php ngi s dng kt ni vo mt my tnh xa v lm vic trn my . Nh dch v ny m ngi ta c th ngi my tnh nh v kt ni vo my c quan lm vic nh ang ngi c quan.Yu cu khi s dng: Phi c mt chng trnh my khch(telnet client program). My ch kt ni phi bt dch v Telnet severVd: Nu my khch s dng h iu hnh Window, bn c th gi lnh Start/ Run v g dng lnh: telnet, nhp vo user name v password ng nhp.5.6. Nhm tin tc- Usenet, newsgroupDch v nhm thng tin News (USENET) y l dch v cho php ngi s dng c th trao i thng tin v mt ch m h cng quan tm. Ngi dng cn ng k (subcribed) vo mt s nhm thng tin no v sau c th kt ni ln server xem cc thng tin trong nhm v ti (load) v trm lm vic xem chi tit, anh ta cng c th gi cc kin ca anh ta ln cc nhm thng tin . T chc nh tn cc News groups: Cc nhm thng tin c nh a ch l mt dy cc tn ca cc News Groups theo th t cha-con. Mi tn mt News groups c phn cch vi tn ca News Group "cha" bng mt du chm . News Group qui nh mt s tn gi nh sau: com Group cha cc thng tin v computer v cc vn lin quan. News Group ny bao gm c cc thng tin v k thut my tnh, phn mm, cc thng tin lin quan ti mng... news Group cp ti cc thng tin v Network News v cc phn mm News. N bao gm mt s News Groups con rt cn thit cho ngi dng l news.newsusers.questions (cc cu hi ca ngi dng)v news.announce.newsusers (cc thng tin quan trng cho ngi dng). Nu bn l mt ngi mi tham gia vo dch v News Groups, bn hy c cc thng tin ny u tin. rec Group cha cc thng tin v vn gii tr, cc hot ng vn ho ngh thut. sci Group cha cc thng tin v nghin cu khoa hc, cc vn mi hay cc ng dng khoa hc (rng hn lnh vc computer trong group comp). News Groups ny bao gm rt nhiu cc News Group con v tng lnh vc khoa hc ring. soc Group cha cc thng tin v cc t chc x hi hay chnh tr cng nh cc thng tin c lin quan. misc Group cha cc thng tin khc, khng thuc cc News Groups bn trn. Trong News Group ny c cha News Group kh c ch l misc.jobs (yu cu tm vic v nhn vic). Nh vy News Group v nhc ng qu s c tn l: rec.music.folk T chc h thng News Groups: Dch v nhm thng tin s dng mt giao thc ca Internet l giao thc NNTP (Network News Transfer Protocol). Cng ging nh hai giao thc Telnet v FTP, giao thc NNTP cng hot ng theo m hnh client/server. Client v Server s lin kt vi nhau qua cng TCP 119. H thng News group m ngi dng nhn thy (client) c mt b phn gi l News Reader lm nhim v kt ni gia chng trnh trn trm lm vic vi server. Thng qua News Reader, ngi dng nhn c t server danh sch cc bi thng tin v cng qua , ngi dng chuyn yu cu ca mnh ln server yu cu ti bi thng tin v. Ngi qun tr News Server c th t to ra cc News Groups trn Server tu theo nhu cu ca ngi dng. y l cc News Groups cc b trn mi Server. Mc d l cc News Groups cc b xong chng vn c th c trao i vi cc server khc nu ngi qun tr cho php. Vic cp nhp thng tin t cc News server khc trn Internet c th c thc hin t ng theo mt lch do ngi qun tr mng ra. Ngi dng ch bit n mt News Server duy nht l server m mnh connect vo. Vic thng tin gia cc server cng nh cc News Groups l trong sut i vi ngi dng. Ngi dng khng cn bit thng tin v News Groups hin mnh ang c l News Group cc b ca server no. Nh vy, vi dch v News Group, ngi dng c th nhn c cc thng tin m mnh quan tm ca nhiu ngi t khp ni sau la gi thng tin ca mnh i cho nhng ngi c cng mi quan tm ny.Cu 6: Trnh by k thut tm kim thng tin trn internet 6.1 Xc nh thng tin v phm vi cn tm kim tm kim thng tin, trc tin cn phi xc nh t kha (Key Words) ca thng tin mun tm kim, y l phn rt quan trng, t kha l t i din cho thng tin cn tm. Nu t kha khng r rng v chnh xc th s cho ra kt qu tm kim rt nhiu, rt kh phn bit v chn c thng tin nh mong mun, cn nu t kha qu di kt qu tm kim c th khng c. Thng thng ch cn nhp t kha mun tm v nhn Tm kim (Search) hoc nhn phm Enter th s cho ra nhiu kt qu tm kim bao gm a ch lin kt n trang Web c t kha v vi dng m t bn di, ch cn nhn tri chut vo a ch lin kt s m c trang Web c thng tin mun tm. 6.2. S dng cc t kha v php ton h tr tm kim m rng cc chc nng tm kim, cng nh to thm nhiu tin dng cho ngi dng, cc Search Engine cng h tr thm nhiu php ton v t kha. D nhin mi Search Engine c th s h tr nhng php ton v t kha khc nhau. y ch nu ra mt s php ton v t kha c bn c h tr bi hu ht cc Search Engine. Dng php + : tm cc trang c mt tt c cc ch ca t kha m khng theo th t no ht th vit ni cc ch ny vi nhau bng du +. Th d: mun tm cc trang ni v cch thc vit Linux scrips bn c th invo tm b t kho Linux +script +tutor

Lm vy th ch c nhng trang no c cc ch nu mi c tm ra. Bng cch ny bn c th lc bt c mt s lng ln cc trang khng cn tm. Dng php - : Trong s cc trang Web tm c do quy nh ca t ha th Search Engine s loi b cc trang m ni dung ca chng c cha ch (hay cm t) ng ngay sau du tr. Th d: Corel Draw -10 :tm kim thng tin lin quan n Corel nhng khng tm thng tin v Corel 10.

Windows Vista" -site:thanhnien.com.vn :Tm cc trang web ni v h iu hnh Windows Vista tr cc trang web ca bo Thanh Nin.

Dng du ngoc kp " " : Khi mun ch th Search Engine nguyn vn ca cm t, c th dng du ngoc kp. Th d: nh nguyn vn mt cu th "Qu cau nho nh ming tru i" vo Google tm xem ai vit cu ny.

T kho mc nhNhiu Search Engine cn h tr thm cc t kho mc nh. Khi dng cc t kho mc nh nh mt thnh phn ca b t kho th cc trang Web c tr v s tho mn cc c tnh chuyn bit ho theo ngha m cc t kho mc nh ny biu tng. Cc h tr ny cho php kim sot c cc loi trang no mun truy tm. Cc t kho mc nh kt thc bng du hai chm : v ch (hay cm t trong ngoc kp) ca b t kho no ng ngay sau du ny s b chi phi bi iu kin ca t kho mc nh, cn cc thnh phn khc trong t kho s khng thay i ngha. Cc t kho mc nh gii hn Search Engine tr v cc trang nm trong mt tn min, hay mt min con. Tu theo Search Engine m cc t kho mc nh c s dng. - Altavista h tr chc nng ny bng t kho host: Th d: host:mars.jpl.nasa.gov mars saturn ch tm trong mars.jpl.nasa.gov tt c cc trang c cha ch mars v ch saturn. - Excite, Google, Yahoo h tr chc nng ny bng t kho site: khi kt hp vi cc lnh khc c th tm theo cch chuyn bit. Th d: "carbon nanotech" -site:www.technologyreview.com cho php tm tt c cc trang no c cha cm t carbonnanotech ngoi tr cc trang xut x t www.technologyreview.com - Tt c Search Engine h tr cc t kho domain, url, site: cho chc nng ny. Th d: tm cc trang v deutch t cc trang trong nc c c th dng deutch domain:.de Cc t kho mc nh dng tm trang c ta cha mt t (hay cm t) c bit: - AltaVista, AllTheWeb, Inktomi (MSN v HotBot) dng t kho title: Th d: title: Mars Landing s gip truy tm cc trang c ta v Mars Landing. - Google v Teoma h tr cc t kho intitle: v allintitle: (allintitle: s nh hng n tt c cc ch ng sau du :). Cc t kho dng tm cc a ch Web no c cha t (hay cm t) ca b t kho: - Google h tr t kho inurl: v allinurl: Mun tm a ch cc trang Web c mt ch c bit th dng inurl. Th d, inurl:nasa s gip tm tt c cc a ch Web no c cha ch nasa. Nu cn truy tm mt i ch c nhiu hn mt ch th dng allinurl: Th d, allinurl:vietnam thetholucbat s gip tm tt c cc trang no m ni dung a ch ca n cha ch vietnam hay l ch thetholucbat. - Inktomi, AOL, GoTo, HotBot cung cp t kho originurl: cho vic ny. - Yahoo th dng t kho u: - Excite dng url: Cc t kho mc nh gip tm cc trang c ci t cc lin kt ti a ch trang c ghi trong t kho: - Google, Yahoo s cung cp t kho link: Tuy nhin, Yahoo yu cu a ch trong t kho phi c tip u ng http:// th mi hot ng hu hiu. Th d: b t kho link:vi.wikipedia.org s gip truy ra tt c cc trang Web no c lin kt ti trang vi.wikipedia.org. - MSN h tr chc nng ny bng t kho linkdomain: Ngoi ra, truy tm cc loi tp c nh dng (format) c bit th c th dng t kho filetype:ui ca tp tin - Google: s h tr truy tm cc kiu tp tin: PDF, Word (.doc), Excel (.xls), PowerPoint (.ppt) v Rich Text Format (.rtf) cng nh PostScript (.ps), Text (.txt), HTML (.htm hay .html), WordPerfect (.wpd) v cc ui khc... Th d: laser filetype:pdf s gip tm cc trang l cc tp tin dng .pdf (.pdf l loi tp tin c dng trong c h s vn bn ca phn mm Adobe Arcobat). - Yahoo cho php tm HTML (htm hay html), PDF, Excel (.xls), PowerPoint (.ppt), Word (.doc), RSS/XML (.xml) v tp tin vn bn dng (.txt). - MSN ch h tr chuyn tm cc loi tp tin: HTML, PDF, PowerPoint (.pps hay .ppt), cc dng ca Word, hay Excel. Lu : i vi cc Search Engine th cc tp tin c ui .htm khc vi cc tp tin c ui .html. Do , nu mun tm mt cch chc chc tt c cc tp tin dng HTML th nn tm lm hai ln, mt ring cho htm v mt cho html. 6.3. S dng cc k t thay th v k t ~ trong b t khoK t thay th (wildcard character) : mt k t c th dng thay th, hay i din cho mt tp hp con ca tp cc k t cha c xc nh hon ton. Mt cch n gin hn, k t thay th l k t c dng i din cho mt k t, hay mt chui k t trong mt t kho, mnh , cu hay dy cc k t. Nhiu Search Engine h tr cho vic s dng hai loi k t thay th. l du sao * v du chm hi ? Du sao * : du ny s thay th cho mt dy bt k cc k t (ch, s, hay du). Th d: trong t kho c t*ng th ch t*ng c th hiu ngm l tng, tng, tung, ttamxng,... Cn lu s khc bit v ngha i vi k t thay th * dng trong cc hiu hnh nh l DOS, LINUX, Windows,... Theo cch hiu ca cc h thng ny th du * hon ton khng b l thuc vo bin gii ca mt t. Trong khi , du * dng trong Search Engine s c hn ch trong bin gii ca mt t. V d: T kho My* dng trong cc cng c tm kim ca cc h iu hnh kiu Windows th n c th l My Downloads, My Documents, My Yahoo!, my_magazines.ico, mysql.php, myth_psychemohop.jpg, mystere,.... Trong khi my* trong cc Search Engine ch gii hn trong cc ch lp thnh bt u vi my. Nh vy, trong v d trn th My Downloads, My Documents, My Yahoo! s khng c Search Engine xem xt m ch c my_magazines.ico, mysql.php, myth_psychemohop.jpg, mystere l hp l m thi. AltaVista, Inktomi (iWon), Northern Light, Gigablast, Google, Yahoo, MSN, ... u h tr cho cch dng du * ny. Du chm hi ? : dng thay cho mt k t duy nht no . Th d: ph?ng c th l phong, phng, ph@ng, ph_ng, ph-ng,... nhng khng th l phng, ph ng, phug, phang. AOL Search, Inktomi (iWon) l cc Search Engine c h tr du ? ny. Du ng ~ : c bit trong Google c mt cch tm khng nhng cc trang c cha t kho m cn tm cc trang c cha ch ng ngha (synonym) Anh ngvi t kho. V d: ~food facts s gip truy tm cc d liu c ch food facts v cc chtng ng nh nutrition facts,... S truy tm theo h tr ny c bit hu dng trong trng hp cc ti liu cn tm qu him hoi. 6.4. Mt s v d tm kim thng tin trn Internet Tm kim video, audio & nh. Video & Audio: Tt nht vo http://baamboo.com tm kim. Kh nng tm kim hiu qu, nht l vi file ting Vit. Ngoi ra c th download v di dng mp3, wma (audio) v dng mp4, avi (video). Tm kim nh c th s dng trang http://images.google.com Tm hiu 1 thut ng (Ting Anh) v cc vn lin quan + S dng http://en.wikipedia.org - ch phn reference, c rt nhiu link hay lin quan + S dng google vi t kho l (define: thut ng) - g define, ri du (:) sau l thut ng Tm kim cc thng tin i sng hng ngy: + Nn ghi nh nhng website c thng tin cn thit. + Trong c 1 website tm ng rt hiu qu l http://diadiem.com.v http://ttvnol.com l ni c rt nhiu thng tin. Tm kim cc thng tin thng thng. + La chn t kho ph hp.Google tm tt c cc ti liu c cha tng t bn g vo mt cch ring l. Mun tm theo cm t th phi thm du nhy kp () u v cui cm t . + Tt nht l chia cm t thnh nhng khi nim ring bit. V d tm kim ni dung Dch t H Ni => Tt nht t kho l: dch t, , H Ni => G vo l (dch t H Ni) - ko c du ng m ngoc + Thm cc la chn khc - (Xem phn tm kim nng cao vi google) Tm sch, ti liu + Tm theo ch , hoc theo 1 quyn sch c th. C cc cch hiu qu sau: S dng t kho l - tn sch download. C th c thm t kho l zip, rar hoc pdf v free S dng t kho l tn sch v ni xut hin l trong tn trang, tn sch v kiu ti liu l pdf, ps hoc doc Tn sch + rapid share (rt hiu qu) - hiu qu hn nu tm theo tn sch c th. Hai cch u c th tm sch theo ch hoc theo tn sch cng c, cch cui tt nu tm theo tn sch, phi mt thi gian mt cht nhng cc k hiu qu. Trong trng hp cha bit tn sch th c th vo mt s trang gii thiu, bn sch nh http://amazon.com tm sch theo ch m mnh mun tm. Ri quay li tm kim. Tm kim nng cao vi google: Trong lc tm kim google, nhn vo ch tm kim nng cao hoc Advance search ta c th c mt s la chn sau: + S kt qu / trang: nn s lng nhiu, 100 kt qu / trang chng hn + nh dng vn bn: nu mun tm slide th l ppt. Nu mun tm sch, ti liu th l pdf hoc ps. + Thi gian c thng tin trn: Nu l tin tc th c th gii hn thi gian ny. + Ni xut hin t kho: Nu mun tm ni dung v ch ny th l trong tn trang, bnh thng th n hin th tt c nhng ni dung c cha t kho thn bi vit. + Tn min, ch ra website mnh mun tm kim: v d nh c th ch nh ch tm kim ttvnol.com hoc 360.yahoo.com hoc website no . Ch l nu ko chn la chn ny. 1 website ch c 2 kt qu duy nht tr v cho mi ln tm kim. Cho d trong website c rt nhiu trang ph hp Cc th thut tm kim Google Tm kim file multimedia -inurl:htm -inurl:html -inurl:php intitle:index of (mpg|avi|wmv) Claudia Schiffer Thay Claudia Schiffer bng t kha cn tm Tm kim phn mm -inurl:aspx-inurl:htm-inurl:html-inurl:phpintitle:indexof (exe|zip|rar|tar|gz|z) IconChanger Thay IconChanger bng phn mm cn tm Search ebook -inurl:htm -inurl:asp -inurl:html (index of|"last modified"|"parent of") AND ("ebook"|"ebooks"|"book"|"books") AND (pdf|chm|doc|txt|zip|rar) AND "Oct-2005" Thay "Oct-2005" bng ebook cn tm Tm kim nhc -inurl:htm -inurl:html -inurl:php -inurl:asp -inurl:doc -inurl:pdf -inurl:shtml -inurl:txt index of mp3 Fresh Fantasy Dizzy Singers Thay "Fresh Fantasy Dizzy Singers" bng file nhc cn tm