10 loi malware in hnhQun Tr Mng - Hin nay, ngy cng c nhiu loi malware mi tinh vi hn, c hi hn xut hin. Ai cng c th bit n nhng tc hi m malware gy ra, nhng khng phi ai cng bit n cch thc hot ng ca chng. Bi vit ny s im ra 10 loi malware c cho l nguy him nht t trc ti nay.Di y l mt s thut ng c s dung jtrong bi vit:

Malware: l mt phn mm c hi c vit ra chuyn xm nhp v ph hy h thng my tnh m ngi dngkhng h hay bit. Malcode: l mt m lp trnh c hi c gii thiu trong sut giai on pht trin ca mt ng dng phn mm v thng lin quan ti s lng malware. Anti-malware:Bao gm nhng chng trnh chng li malware, gip bo v, pht hin v g b malware. ng dng antivirus, anti-spyware v ng dng pht hin malware l nhng v d ca anti-malware.1. Virus

Virus my tnh l mt malware c th ly nhim nhng phi da vo nhng phng tin khc pht tn. Mt loi virus tht s c th lan trn t nhng my tnh b nhim ti mt my tnh cha nhim bng cch nh mt m vo file thc thi c truyn qua nhau. V d, mt virus c th n trong mt file PDF c nh vo mt email. Hu ht virus u gm c 3 thnh phn sau:

Replicator:Khi kch hot chng trnh ch th ng thi virus cng c kch hot, v ngay lp tc chng s pht tn malcode. Concealer:Bin php virus s dng ln trnh anti-malware. Payload:Lng malcode ca mt virus c th c s dng hy chc nng ca my tnh v ph hy d liu.Mt s mu virus my tnh gn y gm W32.Sens.A, W32.Sality.AM, v W32.Dizan.F. Hu ht nhng phn mm chng virus tt s g b virus khi chng c ng k.

2. Su (Worm)

Su my tnh tinh vi hn nhiu so vi virus. Chng c th t ti to m khng cn ti can thip ca ngi dng. Malware s ging su hn virus nu s dng Internet pht tn. Nhng thnh phn chnh ca su bao gm:

Penetration tool: L malcode khai thc nhng l hng trn my tnh ca nn nhn dnh quyn truy cp. Installer: cng c thm nhp gip su my tnh vt qua h thng phng th u tin. Lc , installer a v chuyn thnh phn chnh ca malcode vo my tnh ca nn nhn. Discovery tool: Khi xm nhp vo my, su s dng cch thc truy lc nhng my tnh khc trn mng, gm a ch email, danh sch my ch v cc truy vn DNS. Scanner: Su s dng mt cng c kim tra xc nh nhng my tnh mc tiu mi trong penetration tool c l hng khai thc. Payload: Lng malcode tn ti trn mi my tnh ca nn nhn. Nhng malcode ny c th t mt ng dng truy cp t xa hay mt key logger c dng nh cp tn ng nhp v mt khu ca ngi dng.Tht khng may loi malware ny li sinh si rt nhanh. Khi u vi su Morris vo nm 1988 v hin nay l su Conficker. Hu ht su my tnh c th g b bng chng trnh qut malware, nh MBAM hay GMER.

3. Backdoor

Backdoor ging vi nhng chng trnh truy cp t xa m chng ta thng s dng. Chng c coi nh malware v khi ci t m khng cn c cho php, y lcch m tin tc s dng, theo cc phng thc sau:

Khai thc l hng trn my tnh mc tiu. By ngi dng ci t backdoor thng qua mt chng trnh khc.Sau khi c ci t, backdoor cho php tin tc ton quyn kim sot t xa nhng my tnh b tn cng. Nhng loi backdoor, nh SubSeven, NetBus, Deep Throat, Back Orifice v Bionet, c bit n vi phng thc ny.

4. Trojan horse

Theo Ed Skoudis v Lenny Zelter, Trojan horse l mt chng trnh thot nhn c v hu dng nhng trong n li n cha nhiu tnh nng c hi.

Trojan horse malware cha ng nhiu payload cn tr ci t v chy chng trnh, nh ngn cn malware nhn ra malcode. Mt s k thut che giu bao gm:

i tn malware thnh nhng file ging vi file bnh thng trn h thng. Cn tr ci t anti-malware khng th thng bo v tr ca malware. S dng nhiu loi m khc nhau thay i ng k ca malware nhanh hn nhng phn mm bo mt.Vundo l loi Trojan horse in hnh. N to ra nhiu qung co popup quy ri nhng chng trnh chng spyware, lm suy gim kh nng thc thi ca h thng v cn tr trnh duyt web. c bit, n cn tr ci t chng trnh qut malware trc tip a CD.

5: Adware/spyware

Adware l phn mm to ra trnh n qung co popup m khng c s cho php ca ngi dng. Adware thng c ci t bi mt thnh phn ca phn mm min ph. Ngoi vic lm phin, adware c th lm gim ng k s thc thi ca my tnh. Spyware l mt phn mm thc hin nh cp thng tin t my tnh m ngi dng khng h hay bit. Phn mm min ph thng c rt nhiu spyware, v vy trc khi ci t cn c k tha thun s dng. Mt trng hp ng ch nht v spyware lin quan ti v tai ting chng copy a CD BMG ca Sony.a s nhng chng trnh chng spyware tt s nhanh chng tm ra v g b adware/spyware khi my tnh. Bn cng nn thng xuyn xa nhng file tm, cookies v history t chng trnh trnh duyt Web.

Malware stew

Cho n nay, tt c cc loi malware c bit n u kh khc nhau, gip c th phn bit tng loi. Tuy nhin, loi malware stew ny khng ging nh vy. Nhng ngi vit n nghin cu lm th no kt hp nhng c tnh tt nht ca nhiu loi malware khc nhau nng cao kh nng ca n.

Rootkit l mt v d in hnh ca loi malware ny, n gm cc c tnh ca mt Trojan horse v mt Backdoor. Khi c s dng kt hp, tin tc c th ginh quyn kim sot my tnh t xa m khng b nghi ng.

Rootkits

Rootkit l loi hon ton khc bit, chng thng sa i h iu hnh hin thi thay v b sung nhng phn mm mc ng dng m nhng loi malware khc thng lm. iu ny rt nguy him bi v nhng chng trnh chng malware s rt kh pht hin c chng.

C nhiu loi rootkits, trong c 3 loi c cho l nguy him nht, gm: user-mode, kernel mode v firmware rootkits.

6. User-mode rootkits

User-mode gm nhng on m gii hn truy cp vo ti nguyn phn mm v phn cng trn my tnh. Hu ht nhng m chy trn my tnh s chy trn ch user-mode. V truy cp b gii hn nn nhng ph hy trong user-mode l khng th phc hi.

User-mode rootkit chy trn my tnh vi quyn admin. iu c ngha:

User-mode rootkits c th thay i tin trnh, file, h thng, cng mng v thm ch l dch v h thng. User-mode rootkit t duy tr ci t bng cch sao chp nhng file yu cu vo cng my tnh v t ng khi chy mi khi h thng khi ng.Hacker Defender l mt user-mode rootkit in hnh. Loi rootkit ny v nhiu loi khc b pht hin v g b bi ng dng ni ting ca Luckily Mark Russinovich.

7. Kernel-mode rootkits

Kernel-mode gm nhng m hy gii hn truy cp vo mi ti nguyn phn cng v phn mm trn my tnh. Kernel-mode thng c dng lu tr nhng chc nng tin cy nht ca h iu hnh. Nhng hy hoi trong kernel-modecng khng th phc hi.

T khi rootkit chy trong ch user-mode b pht hin v g b, nhng ngi lp trnh rootkit thay i t duy v pht trin kernel-mode rootkit. Kernel-mode c ngha l rootkit c ci t ng mc vi h thng v nhng chng trnh pht hin rootkit. V vy rootkit c th lm cho h thng khng cn ng tin cy na.

Khng n nh l mt du hiu sa st ca h thng mt kenel-mode rootkit gy ra, thm ch dn n nhng hy hoi khng r nguyn nhn hay treo mn hnh. Lc , bn nn th GMER, mt trong s t cng c g b rootkit c th tin cy, chng li kernel-mode rootkit nh Rustock.

8. Firmware rootkits

Firmware rootkit l loi rootkit ci t tinh vi v nhng ngi pht trin loi rootkit ny nghin cu phng php la tr malcode ca rootkit trong firmware. Mi firmware u c th b thay i, t m vi x l cho ti firmware ca khe cm m rng. iu c ngha:

Khi tt my, rootkit ghi malcode hin thi vo nhng firmware khc nhau. Khi khi ng lai my tnh rootkit cng t thc hin ci t li.Thm ch, nu mt chng trnh pht hin v g b c firmware rootkit, th ln khi ng my tnh sau, firmware rootkit ny vn xut hin hot ng tr li bnh thng.

9. Malicious mobile code (M c di ng MMC)

MMC nhanh chng tr thnh phng php ci t malware vo my tnh hiu qu nht. Chng c th:

Chim quyn my ch t xa. Di chuyn trong mng. Ti v ci t trn mt h thng cc bMMC gm Javascript, VBScript, ActiveX Controls v Flash Animations. Mc ch chnh rt d nhn ra ca MMC l cch thc hot ng, n lm ni dung trang ca trnh duyt web tr nn tng tc hn.

Ti sao MMC li c hi? V vic ci t n khng cn n s cho php ca ngi dng v gy hiu lm cho ngui dng. Ngoi ra n thng l bc m cho mt cuc tn cng kt hp ging nh cng c xm nhp m Trojan horse malware s dng. Sau tin tc c th tin hnh ci t thm nhiu malware.

Cch tt nht chng li MMC l lun cp nht h thng v tt c chng trnh ph.

10. Blended threat (Mi e da hn hp)

Malware c cho l mt blended threat khi n gy ra nhng tn hi ln v pht tn nhanh chng thng qua nhng phn kt hp ca nhiu malcode c mc tiu ring. Blended threat xng ng l mi lo ngi c bit v nhiu chuyn gia bo mt cho rng chng l nhng chuyn gia trong cng vic ca chng. Mt blended threat in hnh c th:

Khai thc v to ra nhiu l hng. S dng nhiu phng thc ti to khc nhau. T ng chy m hy can thip ca ngi dng.Ngoi ra, blended threat malware c th gi mt email dng HTML nhng Trojan horse cng vi mt file PDF nh km cha mt loi Trojan horse khc. Mt s loi blended threat kh quen thuc l Nimda, CodeRed v Bugbear. g b blended threat khi my tnh cn n nhiu chng trnh chng malware, cng nh s dng chng trnh qut malware c ci t chy trc tip t a CD.Trojan & Backdoor ton tp

Trong bi vit ny ti s trnh by vi cc bn v Trojan v Backdoor. Nhng khi nim c bn v Trojan v Backdoor, phn loi v cch thc ly nhim Trojan v Backdoor. Cng vi nhng kin thc khc nh s dng mt s Trojan c bn, cch thc n Trojan vo trong mt file .Exe. Cui cng ti s a ra cc gii php phng chng Trojan v Backdoor.1. Gii thiu v Trojans2. Cc dng v cch hot ng ca Trojan3. Cch nhn bit my tnh b nhim Trojan4. S khc nhau ca cc Trojans5. S dng mt s Trojan tn cng6. n Trojans vo mt file .EXE bnh thng7. Cch pht hin Trojans v Backdoor8. Gii php phng chng Trojan Backdoor9. Kt lun1. Gii thiu v Trojans.- Mt Trojan l mt chng trnh nh chy ch n v gy hi cho my tnh.- Vi s tr gip ca Trojan, mt k tt cng c th d dng truy cp vo my tnh ca nn nhn thc hin mt s vic nguy hi nh ly cp d liu, xa file, v nhiu kh nng khc.

2. Cc dng v cch hot ng ca Trojan- K tn cng c th truy cp c vo cc my tnh b nhim Trojans khi chng Online.- K tn cng c th truy cp v iu khin ton b my tnh ca nn nhn, v chng c kh nng s dng vo nhiu mc ch khc nhau.

- Cc dng Trojans c bn:+Remote Access Trojans Cho k tn cng kim sot ton b h thng t xa.+ Data-Sending Trojans Gi nhng thng tin nhy cm cho k tn cng+ Destructive Trojans Ph hy h thng+ Denied-of-Service DoS Attack Trojan: Trojans cho tn cng DoS.+ Proxy Trojans+ HTTP, FTP Trojans: - Trojan t to thnh HTTP hay FTP server k tn cng khai thc li.+ Security Software Disable Trojan C tc dng tt nhng tnh nng bo mt trong my tnh ca nn nhn.- Mc ch ca nhng k vit ra nhng Trojans:+ Ly thng tin ca Credit Card+ Ly thng tin ca cc ti khon c nhn nh: Email, Password, Usernames,+ Nhng d liu mt.+ Thng tin ti chnh: Ti khon ngn hng+ S dng my tnh ca nn nhn thc hin mt tc v no , nh tn cng, scan, hay lm ngp h thng mng ca nn nhn.

3. Nhng con ng my tnh nn nhn nhim Trojan.- Qua cc ng dng CHAT online nh IRC Interney Relay Chat- Qua cc file c nh km trn Mail- Qua tng vt l nh trao i d liu qua USB, CD, HDD- Khi chy mt file b nhim Trojan- Qua NetBIOS FileSharing- Qua nhng chng trnh nguy him- T nhng trang web khng tin tng hay nhng website cung cp phn mm min ph- N c kh nng n trong cc ng dng bnh thng, khi chy ng dng lp tc cng chy lun Trojans.4. Nhng cch nhn bit mt my tnh b nhim Trojans C bn nht C th khng ng.- CD-ROM t ng m ra ng vo.- My tnh c nhng du hiu l trn mn hnh.- Hnh nn ca cc ca s Windows b thay i- Cc vn bn t ng in- My tinh t ng thay i font ch v cc thit lp khc- Hnh nn my tnh t ng thay i v khng th i li.- Chut tri, chut phi ln nn..- Chut khng hin th trn mn hnh.- Nt Start khng hin th.- Mt vi ca s cht bt raCc Port s dng bi cc Trojan ph bin.- Back Orifice S dng UDP protocol S dng Port 31337 v 31338- Deep Throat S dng UDP protocol S dng Port 2140 v 3150- NetBus S dng TCP Protocol S dng Port 12345 v 12346- Whack-a-mole S dng TCP Qua Port 12361 v 12362- Netbus 2 Pro S dng TCP Qua Port 20034- GrilFriend - S dng Protocol TCP Qua Port 21544- Masters Paradise - S dng TCP Protocol qua Port 3129, 40421,40422, 40423 v 40426.

Cc yu t nh hng ti hiu sut Mng V Tuyn

C nhiu yu t nh hng n hiu sut mng v tuyn ca bn, c th l nhng yu t ngay trong bn cht ca mng chng hn cng ngh ca cc thit b c s dng, mi trng ni vng m cc tn hiu s i qua hay nhng kt ni vt l c bn ng sau truyn dn v tuyn v hn th na. Mt s trong nhng yu t ny khng th trnh c v phi c bin php c gng gim thiu cc nh hng tiu cc m chng tc ng ln hiu sut mng, tuy nhin mt s yu t khc c th c khc phc hon ton qua vic nng cp thit b hay quy hoch mng li tt.C mt s yu t ph bin nh hng n hiu sut mng v tuyn m hu ht mi ngi s d dng xc nh, nhng iu khng lm gim bt tm quan trng ca chng khi xem xt quy hoch mng li, l:Cc yu t hin nhin nh hng ti hiu sut mng v tuyn Cn tr vt l Phm vi mng & Khong cch gia cc thit b Nhiu trong mng v tuyn Vic chia s tn hiuCc yu t c bit n nhiu nh hng ti hiu sut mng v tuyn Ti trng v Cch s dng mng Cc anten c trin khai km Bn cht mi trng ni vng Gii hn v knh ph S phn x ca tn hiu Hn ch ca tn hiu v tuynCc yu t t c bit n hn nh hng ti hiu sut mng v tuyn Gii hn cng sut pht Kh nng tng thch ngc vi cc chun c hn S phn cc ca tn hiu Suy gim tc do cc mo u qun l (overhead) v tuyn Gim hiu sut duy tr kt niCc Yu T Hin Nhin nh Hng Ti Hiu Sut Mng V Tuyn

Cn tr vt l

Tn hiu v tuyn c th gp kh khn khi thm nhp qua cc vt th rn, c th bt k nh l i ni, cc ta nh, bc tng hoc thm ch con ngi. Cng nhiu vt cn gia trm pht v trm nhn th cng nhiu kh nng cng tn hiu b nh hng hn, do bn nn c gng duy tr thng thong cc ng lin kt trong site (line-of-site) tt nht c th. iu ny r rng l khng thc t v gn nh lun c th g trn tuyn truyn dn, nhng bn c th gim thiu nh hng ca n bng cch s dng tn s c th, kh dng cho bn. Nh mt quy lut, tn s cng thp th sng c c im thm nhp cng tt hn. Tuy nhin cng cn phi ni, vi tn s cng cao th kh nng phn x ca sng cng tt, v vy trong mt s trng hp c th li dng yu t phn x ca mt tn hiu thc hin gi n ti trm thu m khng cn phi truyn xuyn qua vt cn.Phm vi mng v Khong cch gia cc thit b

Cc thit b ang hot ng trong mng lun c gng kt ni truyn nhn vi nhau nhiu hn v iu gy ra gim rt cng tn hiu rt nhiu. iu ny l do cch thc lan truyn cc tn hiu v tuyn, ph mt vng rng ln hn khi chng i xa hn v v l do ny nn khi tn hiu tri rng hn, n s tr nn yu hn. Cng tn hiu gim theo quan h nghch o bc ba vi khong cch gia hai thit b.

Do , khi khong cch tng gp i tn hiu s suy yu i 8 ln.Nhiu trong mng v tuynMng v tuyn ang tr nn ngy cng thng dng v do ngy cng nhiu truyn dn v tuyn thc hin truyn nhn qua mi trng khng kh. Nhng tn hiu hot ng cc tn s tng t nhau c th gy nhiu vi nhau v c tc ng tiu cc ng k n hiu sut ca mng. iu ny c ngha l nhng bng tn c s dng ph bin nh cc bng khng cn cp php 2.4GHz c th b nh hng nghim trng bi tnh trng dy c ca cc tn hiu v tuyn, do tai mt im, chng hn mt thit b thu s khng th hot ng d t mc cng sut chp nhn c. Nhng k thut v tuyn khc c th gy nhiu ging nhau nh in thoi DECT v l vi sng l nhng thit b m hot ng cng di tn vi di tn mng WiFi. Nhiu di bng tn ang tr nn kh dng cho hot ng mng v tuyn trnh vn xuyn nhiu ny chng hn nh bng tn khng cn cp php 5GHz, y l mt bng tn ang tr nn kh ph bin. Khi hot ng trong vng mt mng v tuyn cao, bng tn 5GHz c khuyn dng bn thit lp hot ng cho cc mng doanh nghip, cc nh iu hnh, vv xung quanh bn trnh cc vn v nhiu trong tng lai.Vic chia s tn hiuMng v tuyn cho php nhiu hn mt ngi truyn thng giao tip vi mt ngun mng khc ti mt thi im bt k. Vic chia s kt ni ny c ngha l c nhiu thu bao hn s dng mng, nhiu thit b hn c gng kt ni truyn thng vi mt im truy cp trong mt thi im. Cc im truy cp phi y thc nhng ti nguyn ca n ti mi thu bao ring l vi mi lng v tuyn truyn dn cho thu bao hot ng. Thit b c kh nng truyn dn song cng (Full-Duplex) c th truyn v nhn d liu ng thi, trong khi thit b truyn dn bn song cng (Half-Duplex) ch c th gi hoc nhn vo ti mt thi im bt k.Cc Yu T c Bit n Nhiu nh Hng Ti Hiu Sut Mng V Tuyn

Ti trng v Cch s dng mngBn s thy rng cng nhiu thit b client ang s dng bng thng mng th cng t bng thng chia s gia chng. V nhng yu cu bng thng tng ln trong mng ca bn (v d video streaming l mt ng dng chuyn su i hi nhiu bng thng), bn c th mun u t nng cp thit b t c mc phc v cho tc thng lng (hay tc truyn dn d liu hu ch) cao, m bo hiu sut v tin cy mng mc cao.Anten c trin khai kmV anten lm vic bng cch hn ch s tri rng ca tn hiu truyn theo mt hng hoc nh hng c th, nn chng phi c ci t v lp t ng ci thin hiu sut mng. R rng nht l cc loi anten nh hng cao, loi anten m ti cc trm nhn phi tr hng trc tip vo n ly tn hiu, ngoi ra cc loi anten khc phi c nh hng mt cch chnh xc m bo rng chng ang truyn tn hiu trn mt phng chnh xc. Cc anten sector thng phn cc hot ng trn mt mt phng dc hoc ngang v cc anten ng hng (Omni-Directional) s ch truyn tn hiu tt trn mt mt phng nhng trong tt c cc hng.Bn cht ca mi trng ni vngHu ht nhng nh hng l d nhn thy trong cc mng indoor, bn cht kt cu tng c th l mt trong nhng cn tr ln nht ca tn hiu v tuyn. Cc vt liu c s dng c mc nh hng khc nhau, b tng l mt mi ng thng trc trong vic liu c nh hng xu ti hiu sut khi thit lp mng indoor. N gn nh truyn i m khng cho rng cc bc tng dy hn th kh nng thnh cng thp hn, tn hiu s xuyn qua n trong khi duy tr mt cng cao.Gii hn knh phiu ny thng ch nh hng n mng v tuyn hot ng ch nhng di tn s ph bin nh 2.4GHz nhng c th bt u nh hng n di tn 5GHz trong tng lai nu con ngi chuyn sang dng t trn di bng tn ny. Mng v tuyn hot ng trn nhng bng con (sub-band) cn gi l knh m c bng thng nh hn so vi bng thng trong ton b nhng tn s hot ng c th ca chng. Bng tn 2.4GHz c chia thnh 11 knh, mi knh hot ng trn rng knh 25MHz v khong cch gia cc nh knh k cn l 5MHz trong mt di tng th t 2412MHz n 2462MHz. R rng khng mt nhiu tnh ton nhn ra rng cc knh phi chng ln ln nhau c th ph hp trong tng phm vi hot ng. Nhng vng chng ln ny gy ra nhiu nu cc thit b v tuyn ang s dng cc knh ln cn, do cc knh c ngh s dng l ch cc knh 1, 6 v 11, l nhng knh khng chng ln. Tuy nhin, iu ny c ngha l ch c 3 thit b v tuyn c th s dng trong cng khu vc tr khi cc knh chng ln nhau c s dng.S phn x ca tn hiuPhn x tn hiu c bit mt cch chnh xc hn vi nh hng a ng (Multi-Path Fade), thng xy ra trong cc ta nh c b tr cu trc rc ri v phc tp. Cc tuyn ng khc nhau m cc tn hiu thc hin truyn trn c th b phn x mi trng xung quanh gy ra s khc bit trong cc chiu di khong cch tuyn ng m chng i ti trm thu. Khi nhng tn hiu khc nhau ny n trm thu chng c th lch pha nhau v iu ny c th gy ra chng ln sng, t ra nghi vn hoc l m rng kh nng khuch i tn hiu hoc l c th loi b tn hiu ca nhau hon ton. Thi gian m cc tn hiu phn x i ti trm thu l khc nhau do khong cch khc nhau trong cc tuyn ng RF m chng i. S tri rng tr gia cc tn hiu to ra nhiu lin k t ISI (Intersymbol Interference) l mt trng hp trong cc tn hiu b tr bt u gy li k t i trn mt tuyn ng RF ngn hn. Nhng vn ny c th c khc phc bng cch s dng nhng anten phn tp (ci t nhiu hn 1 anten trn my pht vi khong cch c th ph hp) m bo rng nu mt anten hot ng km, nhng anten khc c th s n nh, hoc bng cch khc, s dng cng ngh nh OFDM c th khc phc vn bng cch a ra cc knh sng mang con c chia ra t rng mi bng knh chnh. Nhng knh sng mang con ny gi v nhn d liu ng thi, song song nhau. Vic phn chia nhiu knh nh hn m bo nhiu d liu hn c th c truyn vi mc suy hao thp hn do nhiu tn hiu.Hn ch ca tn hiu v tuynV l do an ninh bn c th mun hn ch vic truyn tn hiu v tuyn ca bn ch cc khu vc m bn mun cung cp c truy cp mng. iu ny c th kh khn bi v vic kim sot s lan truyn tn hiu th khng phi l d dng v n c th i xuyn qua tng vo cc ta nh khc hoc cc khu vc bn ngoi site ph sng thit lp ni m ai c th c gng kt ni d khng c php. Vic gii hn mc cng sut my pht ch ph sng cc khu vc c yu cu l mt trong nhng phng php gii quyt vn ny nhng n s lm gim bt hiu qu, cng tn hiu s b yu i khi ti tt c cc thit b thu. Vic s dng anten nh hng hn ch s tri rng tn hiu cng c th c hiu qu trong vic hn ch vng ph sng tn hiu.Cc Yu T t c Bit n Hn nh Hng Ti Hiu Sut Mng V Tuyn

Hn ch cng sut trm phtNhng quy nh c thit lp bi OFCOM ch ra rng cc thit b hot ng trn di tn s nht nh no phi tun th mc cng sut ng ra my pht ti a. Nhng gi tr ny thay i ph thuc vo tn s thit b ca bn ang hot ng trn, v d 2.4GHz l100mW EIRP v 5GHz th nm trong khong gia 200mW - 4W EIRP, v th bn c th thy rng i vi cc di bng tn khc nhau, bn c th hot ng trn nhng mc cng sut khc nhau. iu ny c nh hng ln n cng tn hiu v trong trng hp tt nht, cc mng c hng li t vic cc thit b hot ng trn mc nng lng cao hn theo quy nh cho php, tng cng cng tn hiu trn mt khong cch di hn. Nu nh hng, khuch i anten c s dng th nhng mc cng sut hot ng c th phi c gim xung bi v OFCOM khai bo gii hn ti a cho mc cng tn hiu lin quan bi cch kt hp anten v card v tuyn pht. Nu s dng mt anten bp sng nh cho nh hng cao, mc cng sut c th phi c gim ng k gi cho truyn dn v tuyn theo nhng quy nh cng tn hiu ti a.Kh nng tng thch ngc vi cc chun c hnHin nay ch c mt nh hng ln trong cc mng hot ng trn chun 802.11. Nu bn s dng xen ln cc thit b 802.11n v mt s cc thit b 802.11b hoc g, k thut mi phi t gii hn tc truyn dn d liu ti a theo cc thit b chun c b v g. Do nn quan tm rng nu bn mun tri nghim y kh nng ca cc chun k thut mi, bn nn thay th tt c cc thit b c hin c v c th hn ch hiu sut mng ca bn. Tc truyn dn d liu ti a trn mng 2.4GHz vi cc thit b 802.11b hin ti: 11Mbps Tc truyn dn d liuti a trn mng 2.4GHz vicc thit 802.11g hin ti v cc thit b khng chun 802.11b: 54Mbps Tc truyn dn d liuti a mi lung trn mng 2.4GHz vi ch cc thit b 802.11n: 150MbpsS phn cc ca tn hiuPhn cc anten nhm nh hng cho cc tn hiu pht v do cc thit b nhn nn c nh hng thu nhn tn hiu trn cng mt phng cho hiu sut ti u. y l iu rt cn thit trong vic thit lp cho tc truyn dn d liu cao, nhim v quan trng cho thc hin lin kt cu kt ni Ethernet im - im (Point-to-Point Ethernet Bridge Link).Suy gim tc do cc mo u qun l (overhead) v tuynDo m ha, bin dch gi v s dng mt phn bng thng knh cho d liu ngi dng, tc truyn dn d liu ti a khng phi l tc truyn dn thc, tc truyn dn d liu hu ch ngoi thc t c tri nghim bi ngi dng cui. Cc mo u qun l (overhead) ca giao thc mng v tuyn thng thng s dn n tc truyn dn d liu thc t ch bng khong mt na tc truyn dn d liu ti a c qung b v iu ny sau c th c gim thm bi cc yu t khc lin quan n vic trang b cc gi d liu. V c bn, tc truyn dn d liu ti a c qung b nhn chung l cao hn nhiu so vi nhng g bn c th tri nghim, nhng mt s nh sn xut vn lit k ra nh l tc thc trn cc sn phm ca h cung cp cho khch hng mt tng tt hn nhng g h mong i t c.Lm gim hiu sut duy tr kt niMt s thit b mng v tuyn c th lm gim tc thng lng hot ng ti cc thit b v duy tr kt ni trong nhng vng tn hiu thp do khong cch tng ln gia cc thit b hoc do nhiu iu ny nh hng n ton b mng li v nhng ngi dng khc m c kt ni vi n v thi gian truyn d liu tng ln gia cc thit b chm hn. Ngoi ra, vic truyn li (retransmission) d liu do rt gi tin cng hn ch s kh dng ca cc im truy cp cho giao tip vi nhng client khc.

Cc loi ng truyn c s dng trn mng Internet1. ng truyn quay s (Dial-Up Line)

Dial-Up Line cung cp s kt ni thng qua PSTN, Dial-Up Line thit lp cc knh mi cho mi cuc gi v c th s dng cc ng i khc nhau i vi cng 1 ch. Do PSTN l mng chuyn mch knh, cc lin kt end-to-end gia hai im cng nh cht lng ca cc lin kt ny l khc nhau i vi mi ln gi, do cht lng ca cc cuc truyn cng rt khc nhau. i vi khong cch ln cht lng knh truyn trn tng on cng rt khc nhau: Tc modem, thng lng ....

2. ng truyn tng t dnh ring (Analog Dedicated Line)

ng truyn tng t dnh ring hoc ng truyn tng t thu bao cung cp cho ngi thu bao knh truyn trc tip end-to-end dnh ring. Khc vi Dial-Up thit lp cc knh khc nhau i vi mi ln gi, cc knh truyn dnh ring c tin cy cao hn v c gi thnh cao hn do chng khng c chuyn mch, lun lun sn sng v lun dnh ring cho ngi thu bao.

3. ng truyn s (Digital Line)

Digial Line c s dng nhm t c tnh lin tc trong kt ni cng nh cht lng ng truyn cao hn. i vi nhiu mng th Dial-Up hoc Analog Line l tuy nhin tn hiu analog thng suy yu do b gii hn bi tn s m thanh. Thm vo cc ting n trn ng truyn c th lm sai lc hoc thm ch t on tn hiu. Sau khi lin kt b t on, hin tng tht c chai (bottleneck) c th xy ra khi lin kt mi c thit lp li.

Khi mt mng WAN chuyn ti s lu chuyn ln hoc cc thao tc khn cp, sai lc d liu v tht c chai s tr thnh cc khon chi bt buc c gi thnh cao. Gii php trnh ting n l s dng ng truyn s thay cho ng truyn analog. ng truyn s thng c gi thnh cao hn, nhng li c tin cy, tc v s an ton thng tin cao hn.

ng truyn DDS (Digital Data Service) tr nn ph bin do cc l do sau:

* DDS thc hin qu trnh truyn ng b gn nh khng c li.

* Tc truyn l: 2400 bps, 4800 bps, 9600 bps v 56 Kbps.

* Lin kt l vnh cu, end-to-end v l hai chiu ng thi.

* Cc cng ty in thoi a phng thng cung cp cc dch v.

4. T-Carrier

T-Carrier l mt loi ng in thoi thu bao tc cao c s dng truyn ting ni v d liu. C bn mc dch v T-Carrier chnh l:

* T1 (1.544 Mbps).

* T2 (6.312 Mbps).

* T3 (44.736 Mbps).

* T4 (274.176 Mbps).

Dch v T-Carrier s dng k thut dn knh cho php dng bit ca cc carrier nh hn (T1) c th c dn vo mt carrier ln hn.

Gii thiu tng quan v Index trong cc h qun tr c s d liu.

I. Gii thiu tng quan v Index trong H qun tr c s d liu1. Cu trc lu tr ca bn ghi(Record)Tt c cc bn ghi(record) ca 1 bng d liu bn trong 1 h qun tr c s d liu n thng c lu tr trn a v kch thc v tnh an ton d liu (trnh cc trng hp li ca phn cng hay phn mm trn h thng lm nh hng ti d liu). Tt c cc record trong 1 bng c t chc trong 1 file v c qun l bi h qun tr c s d liu (khng nh cc file bnh thng c qun l bi h iu hnh). Mi khi c 1 yu cu truy vn d liu th h qun tr c s d liu (DBMS) s xc nh v tr v nhng dng ca cc bng quan h p ng c cu truy vn ca ngi dng, cch thc x l yu cu ph thuc vo cch t chc lu tr cc record trong cc file ny. Nu nhng record dc t chc thnh nhng phn nh v c sp xp theo th t n gn ging nh 1 heap. Trong khi nu nhng record c sp xp theo th t ca 1 vi thuc tnh ca n sau n lu tr file ny theo cu trc file ny c gi l sp xp. truy xut ti nhng dng d liu trong 1 file m c t chc theo heap th a s cc h qun tr c th dng 1 phng php l scan qua tt c cc trang a ni m nhng record c lu tr.Mt khc khi tt c cc record c sp xp trong file th c th s dng phng php tm nh phn trn nhng trang ca a ni cha cc record ly ra cc bn ghi sao cho ph hp vi yu cu ca ngi dng. V cng c dng duy tr trt t c sp xp trong file ny (tm ch thm vo).V d: c 1 danh sch hc sinh c lu trong 1 bng, n s c lu thnh 1 file gi s file ny n sp xp theo th t (last name - tn) th khi truy vn da vo tn th h thng s dng phng php duyt nh phn a ra cc d liu ph hp. Nu chng ta duyt theo yu cu l ngy thng nm sinh th h thng phi duyt qua ht cc dng trong bng (cc trang a, ni cha cc record) a v kt qu cho cu truy vn. Cch lm ny khng c linh hot cho nn khi nim Index trong database ra i gii quyt hn ch ny.

2. Khi nim IndexIndex l mt i tng trong Datatable (h qun tr c s d liu) l 1 cu trc d liu c s dng nhm tng tc tm kim trong 1 table, n ging nh ch mc trong th vin gip cho ngi c tm kim sch mnh cn mt cch nhanh chng v hiu qu hay phn mc lc ca mi cun sch gip ta n ch cn c nhanh hn.v d:

3. Tng quan v Index.Cu trc ca 1 ch mc bao gm t nht 2 phn l Kha tm kim v con tr tr ti mu tin tng ng trong bng d liu.

Index cung cp cho chng ta c 2 phng php truy cp ngu nhin v tun t trn trng d liu c sp xp. Index c th c to ra bng cch s dng 1 hay nhiu trng (field) trong 1 bng (table). V mt khng gian lu tr th 1 index c kch thc nh hn nhiu so vi 1 bng d liu, n m ra kh nng lu tr index trong b nh thay cho 1 bng d liu khi m d liu trong n qu ln.4. Cu trc Index c bn c p dng trong 1 s h qun tr c s d liu hin ti.Cu trc ca Index c th c chia lm 2 loi Clustered v non-clustered.a. Non-Clustered IndexMt non-clustered index l 1 index m trong th t logic ca kho khng ging nh th t vt l ca cc dng trong bngMt index kiu non-clustered thng thng n s cha 1 gi tr tham chiu ti 1 khi (block) d liu, khi d liu ny n cha nhng dng d liu (c th) cho nhng phn t ca ch mc c khi to. ng vi mi vic tm kim ch mc trn ch mc dng ny mt khi d liu m n cha dng cn tm kim th cng phi ly ra.b. Clusterde IndexL mt index m trong th t logic ca cc kho cng tng t nh th t vt l ca cc dng trong bng. (thng khi ta to 1 kho chnh th 1 clustered index s c to trn ct ).Mi khi gom d liu th n s sp xp li bn trong khi d liu gn ging nh th t ca Index bi vy nhng php ton trn cc khi d liu ny n cng tt gn nh l thc hin trn index. Ni 1 cch chnh xc nhng php ton trong 1 h thng c s d liu (database system) l khc nhau nhng v nhng dng d liu ch c th lu cc mc vt l v trong 1 bng d liu ch c duy nht 1 Clustered index c to ra nn n c th lm tng tc truy xut. Nhng ch nhng ni m d liu thng xuyn chng c sp xp ging hay ngc li th t ca Clustered Index hoc khi 1 dy cc phn t c chn.c. S khc bit gia clustere v Non-clustere

PHNG PHP BO MT EMAIL AN TON

* Phng Php 1:Trnh s dng duy nht mt Email

Vic s dng cng lc nhiu ti khon Email s nh lc hng ngi khc khi h khng bit u mi l Email tht m bn thng s dng. Bn c th s dng nhng Email ny ng k cho cc ti khon ng nhp Website, ti khon mng x hi, qun l tn min... thay v ch s dng mt Email ng k cc ti khon .

Trn th trng hin nay, 3 dch v cung cp Email c tnh nng bo mt tt nht phi k n bao gmGmail, MS Outlook v Yahoo! Mail.

*Phng Php 2:S dng mt khu phc tp

Vi nhng mt khu n gin nh111111, 123456, t mt khu da trn ngy sinh... s lm cho cc Email ca bn lun t trn mc bo ng v l nhng mt khu m ai cng c th tm ra nu h nm bt mt s thng tin cn thit v bn.Ngoi ra, vic s dng chung mt mt khu cho tt c cc ti khon ng k cng khng phi l mt hay, tt nht bn nn s dng nhiu mt khu v nhng mt khu phi c di nht nh v tng i phc tp.

*Phng Php 3: mt ti Phishing la o

Phishing l thut ng khng cn qu xa l i vi nhng ngi thng xuyn lt Web, y l cch thc m cc Hacker chuyn nghip thng s dng nhm mc ch ly cp cc thng tin ti khon nh mt khu, ti khon giao dch trc tuyn... Nu nh mt lc no bn nhn c mt Email yu cu nhp thng tin ti khon th tt nht nn trnh xa nhng Email kiu ny, ng di m nhp thng tin c nhn ca mnh vo Email .

Cch thc ly ti khon ca dng Phishing la o ny nh sau: Cc Hacker mo danh mt Website no ( thng l nhng Website ni ting nhFacebook, Amazon...) nh la ngi dng.

*Phng Php 4:Cng t nhp link nh km Email cng tt

Cch nhn bit nhng Email nguy him chnh l nhng Email n t nhng a ch khng xc nh hoc thng l nhng Email rc. Nhng Email ny thng c ni dung qung co v km theo nhng ng Link yu cu bn phi click vo ng nhp. Tuy nhin, bn ng vi click ngay vo nhng Link trong nhng Email dng ny v rt c th nhng ng dn ny s dn bn n nhng Website c cha m c, Virus v cc phn mm c hi... Ngoi tr l Email n t cc ngn hng hoc cc dch v m bn ang s dng.

* Phng Php 5:Khng m file nh km khi khng xc nh r ngi gi

Nu bn nhn c mt Email t mt ngi m bn khng quen bit cha cc file nh km v nu bn l ngi t m th chc hn khi ti xung nhng tp tin dng , cc m c hi s lp tc lan truyn n my tnh ca bn. y l nhng tp tin m khi bn click vo s t ng ti v hoc mt s file nh dng EXE nhng c t di cc nh dng nh ph bin nh JPG hay GIF...

*Phng Php 6:Thng xuyn qut Virus trn my tnh

My tnh ca bn nn trang b mt phn mm dit Virus nu khi chng may click vo mt lin kt trong Email dng Phishing la o th nhng phn mm ny s t ng thng bo mi khi pht hin ra Virus v cc m c hi bn c bin php nhanh nht ngn chn s ly lan ca chng.

Bn c th chn la v download mt trong10 phn mm dit Virut tt nht 2014.*Phng Php 7:Hn ch kt ni WiFi cng cng

Kt ni WiFi ti cc t im cng cng chng hn nh cc qun Cafe s gip bn cp nht v truy cp Internet mi lc, mi ni. Tuy nhin, nu bn ch lt Web bnh thng th khng sao nhng nu bn thng xuyn truy cp vo cc ti khon giao dch trc tuyn th c th s b cc phn mm gin ip " nh hi" c nhng g bn ang lm v ang lm ti u.

Kt lun:Trn y ch l 7 phng php trong s rt nhiu phng php bo mt Email an ton. Nu nh thi quen ca bn l mt trong nhng vn c cp trong bi vit ny th tt nht nn sa li ngay trc khi nhng vic ng tic c th xy ra.

L hng Zero DayL hng zero day l mt thut ng ch nhng l hng cha c cng b hoc cha c khc phc.Li dng nhng l hng ny, hacker v bn ti phm mng c th xm nhp c vo h thng my tnh ca cc doanh nghip, tp on nh cp hay thay i d liu.H qu l c c mt th trng ch en giao dch, mua bn l hng Zero-day ht sc ng vui, nhn nhp trn mng Internet.Tui th trung bnh ca mt l hng zero-day l 348 ngy trc khi n c pht hin ra hoc v li, nhiu l hng thm ch cn sng "th" hn th. Bn ti phm mng sn sng tr khon tin rt ln mua li cc l hng zero-day.Cn tn cng "Zero Day", theo Burleson Consulting, c nh ngha nh l mt cuc tn cng din ra trong mt thi gian ngn, thng cha n mt ngy (do c thut ng "zero day"). Cuc tn cng zero day c o din cn thn ti a ha thit hi trong mt ngy bi v cc cng c dit virus truyn thng (phn mm v) khng c thi gian phn ng.Cookie l mt dng bn ghi c to ra v lu li trn trnh duyt khi ngi dng truy cp mt website. Chng l bn nhng cng c th l th vi ngi lt web.Bi vit ca cc chuyn gia ca cng ty bo mt CMC InfoSec s gii thiu nhng thng tin ngi dng cn bit nhn thc r vn ring t v bo mt, quan trng l phi hiu c mc ch ca cookie.Bn c th bt gp cookie ca trnh duyt gn nh khp mi ni mi khi lt web. Hin nay, ngi dng ang tranh ci v bn cht ca nhng tp tin ny, c ngi cho rng cc cookie ha hn mt web thn thin hn, mt s khc li cho rng chng mang mt mi him ha e da n s ring t c nhn.Cookie l g?Cookie l mt b nhc nh m website lu tr trn my tnh ca bn c th nh danh cho bn. Khi bn truy cp v mt trang web, website ny s t mt cookie ti trn my , thay cho vic lin tc hi bn cc thng tin nh nhau, chng trnh trn website c th sao lu thng tin vo mt cookie m khi cn thng tin s c cookie. Nu khng c cookie bn s phi nhp li thng tin ca mnh trn mi mn hnh web. Thng tin duy nht m cookie lu tr l thng tin m bn thn bn chia s vi website to ra cookie. Mt website khng th c cookie ca mt cng ty khc tr khi cng ty kia cung cp cho cng ty cha kha gii thch ngha ca cookie.Cookie c cc loi sau:- Session Cookie: c lu trong b nh ca my tnh ch trong phin duyt web v s t ng xa khi my tnh khi trnh duyt ng li. Nhng cookie ny thng c lu tr di dng ID. N cho php bn nhanh chng chuyn ti mt trang mi m khng cn ng nhp li. Chng c s dng rng ri nhng trang web thng mi. V d: theo di cc bn ghi m ngi tiu dng thm vo gi hng- Persistent Cookie: c lu tr trn cng ca my tnh v khng b xa khi trnh duyt ng li. Nhng cookie ny c th thit lp nhng s thch ca bn i vi mi trang web c th khi bn quay li, cho php nhng u i s c s dng trong nhng ln trnh duyt tip theo.Persistent Cookiec th c s dng nhn dng bn, phn tch hnh vi ca bn khi lt web. Chng cng c th c s dng cung cp thng tin v s lng khch hng truy cp, thi gian trung bnh cho mt trang c th, ng nhp thng tin c lu tr trong ti khon hiu sut ca web.- Cookie ca mt hng th 3: Cookie cho php cc cng ty tip th hoc qung coLi ch ca cookieCc cookie c s dng trong cc dch v thng mi in t h tr chc nng mua hng trc tuyn, my ch c th theo di khch hng v sao lu cc giao dch ca h khi h di chuyn trong sitei vi nhng doanh nghipDoanh nghip c th bit c mt s thng tin v nhng ngi ang truy cp web ca mnh, bit c mc thng xuyn truy cp cng nh thi gian chi tit truy cp.Doanh nghip c th bit c s cm nhn ca bn khi duyt web . Lu tr thng tin c nhn ca khch hng, nhng thng tin ny s gip khch hng khi vo trang web ln sau s thun tin hn.Doanh nghip s dng cookie iu chnh cc qung co ca mnh, cung cp cho bit nhng qung co no c xem nhiu nht t a ra bin php iu chnh hoc thit k ph hp.i vi ngi dngChng lm cho web tin li hn, ngi dng c th truy cp vo web nhanh hn khng phi nhp li cc thng tin nhiu ln.Nhng ri ro m Cookie mang liMc d bn thn cookie thng tr rt hu ch v thun tin nhng km theo l nhng ri ro c lin quan c lu tr.Cookie nh hng ti s ring t ca ngi dng. cng nh r r thng tin c nhn. Cookie theo di ngi dng gh thm nhng ni no v xem nhng g trn web. Bn thn cc cookie khng th dng pht tn virus, m c. Tuy nhin n c th thu thp kh nhiu thng tin c nhn ca bn nht l nhng thng tin bn cung cp trn trang web nh thng tin th tn dng nn cookie c th lm tng nguy c mt thng tin ng nhp nu nh ngi khc s dng my tnh ca bn, hoc trng hp my tnh ca bn b xm nhp, nh cp.

Quy hoch b nh trong WindowsBch khoa ton th m WikipediaQuy hoch b nh trong Windowsl hnh thc ngi s dng vh iu hnhWindowsquy hoch qun l s dng ng thi nhiu loib nh.Mc lcS dng b nh trong h iu hnh[sa|sa m ngun]B x l trung tm (CPU) l thit b x l chung cho cc tc v ca mt my tnh(xem thmCPU), trong qu trnh lm vic ca CPU lun cn x l vi d liu, ni mt cch n gin hn th CPU lm vic vi cc d liu v lnh a vo bin chng thnh kt qu mt cch trc tip hoc thng qua cc thit b khc h tr cng x l vi n.Trong qu trnh x l vid liu, quy trnh s dng d liu bt u t chnh b nh m (cache) gn n nht (cache c th nm trong CPU ngy nay, nm gn n vi cc CPU gn trn th cm mt hngslot 1hoc trnbo mch chtrong cc thi gian trc y). Nucachekhng c d liu cn thit, CPU s tm n b nh chnh (RAM). Nu vn cha thy, chng tm trn cc b nh chm hn nh trn a cngv cc thit b nh cn li.CPU lm vic hon ton theo s qun l cah iu hnh, do vic tm kim v x l trn ph thuc vo h iu hnh. H iu hnh c th quy hoch b nh cho h thng sao cho mi qu trnh lm vic caCPUl ti u nht cho n thi im ra i ca h iu hnh v nng lc, tp lnh ca CPU.Cc dng b nh v thit b lu tr[sa|sa m ngun]Bi chi tit:B nhB nhtrong cng ngh my tnh l t dng cho cc thit b c kh nng lu tr d liu khi c cung cp nng lng hoc khi ngng cung cp nng lng cho chng. Tu theo tng dng lu tr d liu ph thuc vo nng lng cung cp cho thit b m c th chia ra theo cc th loi:Phn chia theonng lngcung cp Nhm b nh ch lu tr d liu khi c cung cp nng lng. Nhm ny gm: RAM, cache trong b x l Nhm b nh lu tr d liu ngay c khi ngng cung cp nng lng. Nhm ny bao gm: Cc loi a(vt l), ROM, Phn chia theo hnh thc s dng ca Windows B nh chnh:RAM B nh lu tr c nh: a cng B nh lu tr di ng: a mm, a quang, USB flashS dng b nh chnh[sa|sa m ngun]B nh chnh (RAM) l ni h iu hnh s dng cho ton b cc qu trnh chun b d liu cho CPU s dng nhm m bo cho h thng lm vic mt cch nhanh v ti u nht. Thng thng b nh chnh s c np ton b d liu m c d on.Tu theo dung lng b nh chnh hin c m h iu hnh c th thc hin vic lu d liu ln chng mc no. Mi h iu hnh u c mt yu cu ti thiu v kch thc ca b nh chnh m nu nh khng t thng s ny th hoc h iu hnh khng th lm vic c, hoc l chng hot ng rt chm v thng xuyn xy ra li.Tuy nhin, nu nh dung lng RAM qu ln th h iu hnh c th khng qun l c chng, chng hn cc h iu hnhWindowsphin bn thng dng (32 bit) ch h tr gii hn di 3 GB dung lng b nh chnh. iu ny lin quan n vic cp pht cc a ch b nh gii hn trong 32 bit, cc h iu hnhWindowsphin bn 64 bit hon ton khc phc c gii hn ny nu bn dng ti 4GBdung lng RAM tr ln.S dng b nh hon i[sa|sa m ngun]S dng b nh hon i l hnh thc h iu hnh s dng cc b nh chm hn thay cho b nh chnh.H iu hnh Windows s s dng cc dng b nh cn li cha mt phn d liu ca b nh chnh ln n di dng tp tin (file) gi l tp tin hon i (swap file). Theo mc nh tp tin ny s c t cng phn vng vi h iu hnh. Windows 9X tp tin ny c tn: win386.swp (trong th mc WINDOWS), hwindows NTn c tn pagefile.sys (nm trn phn vng ci t h iu hnh, khng nm trong th mc Windows ging nh h Win9X).Nu mt tc v bt k cn n mt lng b nh trng ( cho chng lm vic) ln hn so vi lng b nh trng cn li, h iu hnh s chuyn mt phn d liu trn RAM vo tp tin hon i. Nhng d liu c chuyn sang tp tin hon i thng l cc d liu t c CPU s dng hn trong RAM (hoc vn thuc dng np sn m cha s dng n). Nu nh tc v ang thc hin cn n d liu c chuyn sang tp tin hon i th h iu hnh li c d liu t tp tin ny. Nh vy cho thy rng nu nh h thng c mt lng RAM nh th c nhng thi im hot ng rt chm, h thng truy xut d liu ti a cng lin tc(th hin qua n bo truyn d liu quaIDEtrn thng my nhp nhy lin tc).Nu nh mt h thng c hai a cng vt l tr ln, c th di chuyn tp tin hon i sang mt phn vng ca a cng cn li (khng ci h iu hnh) ti u hn bi khi ny h iu hnh c th ng thi truy xut cc d liu khc trong cc th mc cha phn mm v h iu hnh, ng thi c/ghi trn tp tin hon i.y cng l mt nguyn l cc phn mm c cng dng nh "gii phng b nh h thng" lm. n gin l phn mm yu cu mt lng b nh RAM rt ln (n theo mc thit t ca ngi s dng) h iu hnh dn cc d liu cha s dng vo tp tin hon i. Sau phn mm ny gii phng ton b b nh yu cu, v khi ny lng b nh vt l trng tng ln. Thc cht th vic ny cng lm tng i cht hiu nng v gip cho h iu hnh khng np mt s phn d liu s khng s dng, cc phn d liu ca cc phn mm khc sau khi b li vn tn ti. Nu nh sau khi thc hin m ngi s dng li bt u s dng cc phn mm trc dng th h iu hnh li c chng t tp tin hon i np ngc li chng vo RAM.H iu hnh Windows h NT (i din 9X ch c duy nht trn Windows Me) cn s dng mt dng hon i khc ch "ng ng" (hibernate). Trc khi chuyn sang ch ng ng, ton b ni dung ca RAM trong thi im s c ghi li thnh mt tp tin trn a cng c tn hiberfil.sys v c dung lng ng bng dung lng ca RAM h thng. Tp tin ny khng c chc nng nh tp tin pagefile.sys, c ngha l nu khng cn s dng ch "ng ng" th bn c th tt chc nng ny (trongPower OptiontrongControl Panel, vo tabHibernatev b chn Enable Hibernate) xo tp tin ny (ch chng l tp tin n) tit kim dung lng b nh (mt s h iu hnh t xo chng sau khi khng kch hot chc nng ny).Hnh ng "ng ng" ca h iu hnh hon ton khc so vi cc ch stand by. Trang thi ny ghi li ton b qu trnh lm vic hin ti ca h iu hnh ln a cng, sau ngi s dng c th tt my, rt in. Khi phc hi li trng thi trc khi ng ng, h iu hnh li np ngc li t a cng vo RAM. Do hnh ng "ng ng" khng ph hp nu nh bn mi lp thm mt thit b phn cng mi hoc ci t phn mm m cn thit phi khi ng li h thng thit lp ch lm vic mi.Cc vng b nh o khng mc nh[sa|sa m ngun]Cc vng b nh o khng mc nh l cc vng b nh, ng dn khng phi do h iu hnh Windows to ra trong qu trnh ci t hoc hot ng, chng hon ton do ngi s dng to ra hoc dng mt phn mm ca hng th ba thc hin. Vng b nh o thng dng m rng thng s k thut m cc thit b thc khng p ng c hoc khng ti u so vi cc vng b nh o to ra.Phn vng a cng oTo phn vng o ging nh cc phn vng trn a cng m c th gn mt k t ln n (to ra mt ng dn c thc) l mt phng thc hu hiu cho mt s cng vic cn n mt phn vng l tng (c tc c v ghi nhanh). Chng c th cn thit v hiu qu i vi mt s ng dng cn n c v ghi d liu nhanh, chng hn ni cha d liu tm thi cho cc trnh duyt lt web.Cc phn vng o c ly mt phn dung lng ca RAM do chng c tc c v ghi nhanh tng ng tc ca loi RAM trong h thng. a quang o a quang o l hnh thc to ra mt a quangkhng c tht m h iu hnh hoc cc phn mm c th coi chng l mt a quang vt l thc s. Do tc lm vic ca a cng lm vic nhanh hn so vi cc a quang, do nu mt phn mm lm vic cn n a quang c d liu (chng hn mt s game ch chy khi c aCD/DVDnm trong ) nn ngi s dng to ra hoc thng qua phn mm ca hng th ba to ra mt a quang o m cc d liu trong "a quang" li nm trn a cng.Gn k t cc loi b nh hin hu[sa|sa m ngun]Cc b nh s dng trong Windows c th ng thi cng hot ng cc phng thc khc nhau, phn b nh m ngi s dng c th can thip c t cc thit b nhp d liu (bn phm, chut) Windows s gn cho chng mt k t thun tin cho vic phn bit, v s dng. (Lu : Gn k t cc b nh l mt khi nim khc via ch b nh)K t gn c s dng cc ch ci vit hoa theo bng ch citing Anh, bt u s dng t chAtr i v c th c t n k t cui cng trong bng lZ. Khng th i cc k t ny sang cc ch ci ca ngun ng khc (chng hn ch trong tin Vit)Mi vng, loi b nh ch s dng duy nht mt k t ng ring l. k hiu cc cch gn k t, h iu hnh h Windows quy c nh sau:Tn k t gn cho phn vng, hoc a + du hai chm (:) + k t gch cho (\)V d:A:\ a mm c gn l AC:\ a khc (thng l a cng), c gn l C.Vic gn k t cho cc loi, dng b nh ch c gi tr i vi tng h iu hnh c ci t trn my tnh. Khi c nhiu h iu hnh cng ci t trn mt my tnh th cc phn vng b nh c gn vi cc tn khc nhau i vi ring tng h iu hnh. Chng hn mt phn vng ca a cng c th c gn k t D h iu hnh ny li c gn k t C, E, F h iu hnh khc.Thi im xut hin ca cc k t nh hng n k t c gn. Nu nh mt my tnh c gn ng thi hai a cng vt l, h iu hnh h NT s gn hai phn vng u tin trc ln lt l C, D ri ln lt n cc phn vng th hai, baca tng a. Nu nh sau qu trnh ci t, ngi s dng mi gn thm mt a cng na th cc phn vng s gn ni tip theo sau a cui cng (sau c quang, do khng thun tin vi thi quen rng cc a quang th c gn cc k t cui cng.K t gn cho a mm[sa|sa m ngun]H iu hnh Windows cc phin bn (vMS-DOS) u dnh ring hai k t gn cho a mml A v B. iu ny c ngha l cho d khng c a mm no th cc dng b nh cn li khng c gn cc k t ny.K t gn cho cc dng b nh cn li[sa|sa m ngun]Tt c cc dng lu tr d liu cn li ngoi mm u s dng k t bt u t ch ci C tr i ln lt cho n ch Z. Phn di y trnh by vic gn k t cc loi b nh do h iu hnh Windows t ng thc hin ngay trong qu trnh ci t h iu hnh v ln khi ng u tin sau khi ci t.Th t u tin ca vic gn bao gm:Cc phn vng(partition)ca a cng:c gn bt u bng ch C tr i cho n ht cc phn vng c th nhn bit c trong mt h iu hnh h Windows. iu ny c ngha l mt phn vng c thit lp n hoc c nh dng m h iu hnh khng nhn bit c th s khng c gn k t. V d: Trong h iu hnh Windows 9X(9X l vit tt ca cc h iu hnh:Windows 95cc phin bn,Windows 98cc phin bn vWindows Me)khng th s dng c cc phn vng nh dngNTFSch ph hp vi h iu hnh h NT (NT/2000/XP/Vista) nn chng s khng gn cho cc phn vng ny.Cc a quang:Cc a quang c t ng gn k t tip theo sau cc phn vng ca a cng c gn tn.Cc dng b nh cn li:Cc dng b nh cn li bao gm: a gn ngoi, USB flash, cc u c th nh, cc thit b ngoi vi khc cn truy xut d liu thng qua h iu hnh Windows (my nh s, camera, digital cam). y l cc dng b nh khng thng xuyn c kt ni vi h iu hnhTt c cc dng b nh ny khng c mt quy c no c bit, chng ln lt c h iu hnh Windows gn cc k t tip theo. Vic gn cc k t cho cc loi a ny khng c c nh, nu cng c xut hin trong mt thi im th cc k t ny c gn theo th t tip theo nhau theo bng ch ci.Thay i cc k t c gn[sa|sa m ngun]Mc d Windows t ng gn cc k t b nh nhng trong mt s phin bn ca h iu hnh Windows c th cho php ngi s dng i tn cc k t c gn cho cc vng b nh. V d trong Windows XP, ngi s dng c th quy hoch li cch gn k t bng tin ch Disk Management ca Windows h NT. Vic quy hoch li thng l gip cho cc phn vng khng b i tn trong cc ln ci t h iu hnh hoc gip ng nht k t c gn cc h iu hnh khc nhau c ci t cng trn mt my tnh. Khi ny tt c cc shortcut s c ng nht v s dng c trn ng thi cc h iu hnh m khng gp li.Tuy nhin, vic thay i cc k t c gn cho cc phn vng ca a cng li khng thc hin ti mt s phn vng c lin quan n h iu hnh: Chng hn i vi chnh phn vng ci t h iu hnh s khng i c k t, phn vng cha cc tp tin khi ng h iu hnh v phn vng cha tp tin swap. Thng thng th vi vic ci t theo mc nh (khng la chn li so vi ngh ca h iu hnh) hoc trn mt my tnh ch ci t duy nht mt h iu hnh th cc phn vng nh trn s cha y : Cc tp tin phc v khi ng, tp tin hon i b nh, v h iu hnh s cng nm ti mt phn vng u tin v c gn tn l C.Vic tin hnh thay i k t gn c th thc hin trong Disk Management khi nhp chut phi vo phn vng cn i k t v chn vo mc"Change Drive Letter an Patths". Bn c th thay i thnh tn ca bt k mt k t no cha c s dng (tr A, B) hoc c th b tn k t ca chng (khi ny phn vng s tr thnh n vi h thng nhng ng nn lm dng iu ny bi c th thc hin iu thng qua mt phng thc khc n gin hn v khng lm mt mt phn vng trong h iu hnh -chng hn c th dng TeawkUI).Phn loai mng[sa|sa m ngun]LAN[sa|sa m ngun]LAN(tAnh ng:local area network), hay cn gi l "mng cc b", l mng t nhn trong mt to nh, mt khu vc (trng hc hay c quan chng hn) c c chng vi km.[4]Chng ni ccmy chv ccmy trmtrong cc vn phng vnh my chia s ti nguyn v trao i thng tin.LANc 3 c im:1. Gii hn v tm c phm vi hot ng t vi mt cho n 1km.2. Thng dng k thut n gin ch c mt ng dy cp (cable) ni tt c my. Vn tc truyn d liu thng thng l 10Mbps, 100 Mbps, 1 Gbps, v gn y l 100Gbps.[5]3. Ba kin trc mng kiu LAN thng dng bao gm: Mng bus hay mng tuyn tnh. Cc my ni nhau mt cch lin tc thnh mt hng t my ny sang my kia. V d ca n lEthernet(chunIEEE802.3). Mng vng. Cc my ni nhau nh trn v my cui li c ni ngc tr li vi my u tin to thnh vng kn. Th d mng vng th biIBM(IBM token ring). Mng sao.MAN[sa|sa m ngun]

Mng th vin trong nhnh m hnh cy v vic kim sot cc ti nguyn mngMAN(t Anh ng:metropolitan area network), hay cn gi l "mng th", l mng c c ln hn LAN, phm vi vi km. N c th bao gm nhm cc vn phng gn nhau trong thnh ph, n c th l cng cng hay t nhn v c c im:1. Ch c ti a hai dy cp ni.2. Khng dng cc k thutni chuyn.3. C th h tr chung vn chuyn d liu v m thoi, hay ngay c truyn hnh. Ngy nay ngi ta c th dng k thutcp quang(fiber optical) truyn tn hiu. Vn tc c hin nay th t n 10 Gbps.V d ca k thut ny l mng DQDB (Distributed Queue Dual Bus) hay cn gi l bus kp theo hng phn phi (tiu chun IEEE 802.6).WAN[sa|sa m ngun]

Cc kiu ni trong WANWAN(wide area network), cn gi l "mng din rng", dng trong vng a l ln thng cho quc gia hay c lc a, phm vi vi trm cho n vi ngn km. Chng bao gm tp hp cc my nhm chy cc chng trnh cho ngi dng. Cc my ny thng gi l my lu tr(host) hay cn c tn lmy ch,my u cui(end system). Cc my chnh c ni nhau bi ccmng truyn thng con(communication subnet) hay gn hn lmng con(subnet). Nhim v ca mng con l chuyn ti ccthng ip(message) t my ch ny sang my ch khc.Mng con thng c hai thnh phn chnh:1. Cc ng dy vn chuyn cn gi l mch (circuit), knh (channel), hay ng trung chuyn (trunk).2. Ccthit b ni chuyn. y l loi my tnh chuyn bit ho dng ni hai hay nhiu ng trung chuyn nhm di chuyn cc d liu gia cc my. Khi d liu n trong cc ng v, thit b ni chuyn ny phi chn (theo thut ton nh) mt ng dy ra gi d liu i. Tn gi ca thit b ny lnt chuyn gi(packet switching node) hayh thng trung chuyn(intermediate system). My tnh dng cho vic ni chuyn gi l "b chn ng" hay "b nh tuyn" (router).Hu ht cc WAN bao gm nhiu ng cp hay l ng dyin thoi, mi ng dy nh vy ni vi mt cp b nh tuyn. Nu hai b nh tuyn khng ni chung ng dy th chng s lin lc nhau bng cch gin tip qua nhiu b nh truyn trung gian khc. Khi b nh tuyn nhn c mt gi d liu th n s cha gi ny cho n khi ng dy ra cn cho gi c trng th n s chuyn gi i. Trng hp ny ta gi l nguyn l mng con im ni im, hay nguyn l mng con lu tr v chuyn tip (store-and-forward), hay nguyn l mng con ni chuyn gi.C nhiu kiu cu hnh cho WAN dng nguyn l im ti im nh l dng sao, dng vng, dng cy, dng hon chnh, dng giao vng, hay bt nh. hnh mng[sa|sa m ngun]Bi chi tit:Cu trc lin kt mngMng hnh sao (Star Network)[sa|sa m ngun]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. Ty theo yu cu truyn thng trn mng m thit b trung tm c th l hub, switch, router hay my ch trung tm. Vai tr ca thit b trung tm l thit lp cc lin kt Point to Point. u im l 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 l di ng truyn ni mt trm vi thit b trung tm b hn ch (bn knh khong 100m vi cng ngh hin nay).Mng tuyn tnh (Bus Network)[sa|sa m ngun]C tt c cc trm phn chia trn 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 PointtoMultipoint hay Broadcast. u im: D thit k v chi ph thp. Khuyt im: Tnh n nh km, ch mt nt mng hng l ton b mng b ngng hot ng.Mng hnh vng (Ring Network)[sa|sa m ngun]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 PointtoPoint gia cc repeater. u im: Mng hnh vng c u im tng t nh mng hnh sao. Nhc im: Mt trm hoc cp hng l ton b mng b ngng hot ng, thm hoc bt mt trm kh hn, giao thc truy nhp mng phc tp.Mng kt hp[sa|sa m ngun]Kt hp hnh sao v tuyn tnh (Star Bus Network): Cu hnh mng dng ny c b phn tch tn hiu (splitter) gi vai tr thit b trung tm, h thng dy cp mng cu hnh l Star Topology v Linear Bus Topology. Li im ca cu hnh ny l mng c th gm nhiu nhm lm vic cch xa nhau, ARCNET l mng dng kt hp Star Bus Network. Cu hnh dng ny a li s uyn chuyn trong vic b tr ng dy tng thch d dng i vi bt c to nh no.Kt hp hnh sao v vng (Star Ring Network): Cu hnh dng kt hp Star Ring Network, c mt "th bi" lin lc (Token) c chuyn vng quanh mt ci HUB trung tm. Mi trm lm vic c ni vi HUB l cu ni gia cc trm lm vic v tng khong cch cn thit. Mng hnh vng Mng tuyn tnhCc phng php truyn tin[sa|sa m ngun]Mng chuyn mch knh (Circuit Switching Network)[sa|sa m ngun]Bi chi tit:Chuyn mch knhKhi c hai trm cn trao i thng tin vi nhau th gia chng s c thit lp mt "knh" c nh v c duy tr cho n khi mt trong hai bn ngt kt ni. D liu ch c truyn theo con ng c nh ny. 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 l 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 l phi tn thi gian thit lp ng truyn c nh gia hai trm; hiu sut s dng 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.Mng chuyn mch thng bo (Message Switching Network)[sa|sa m ngun]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).Mng chuyn mch gi (Packet Switching Network)[sa|sa m ngun]Bi chi tit:Chuyn mch giK 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.M hnh ng dng mng[sa|sa m ngun]M hnh mng ngang hng (PeertoPeer Network)[sa|sa m ngun]Bi chi tit:Mng ngang hngMng peertopeer l mt v d rt n gin ca cc mng LAN. Chng cho php mi nt mng va ng vai tr l thc th yu cu cc dch v mng (client), va l cc thc th cung cp cc dch v mng (server). Trong mi trng ny, ngi dng trn tng my tnh chu trch nhim iu hnh v chia s ti nguyn ca my tnh mnh. M hnh ny ch ph hp vi cc t chc nh v khng quan tm n vn bo mt. Phn mm mng peertopeer c thit k sao cho cc thc th ngang hng thc hin cng cc chc nng tng t nhau.Cc c im ca mng peertopeer l mng peertopeer cn c bit n nh mng workgroup (nhm lm vic) v c s dng cho cc mng c 10 ngi s dng (user) lm vic trn mng ; khng i hi phi c ngi qun tr mng (administrtor); trong mng peertopeer m ngi s dng lm vic nh ngi qun tr cho trm lm vic ring ca h v chn ti nguyn hoc d liu no m h s cho php chia s trn mng cng nh quyt nh ai c th truy xut n ti nguyn v d liu .u im l n gin cho vic ci t v chi ph tng i r.Nhc im l Khng qun tr tp trung, c bit trong trng hp c nhiu ti khon cho mt ngi s dng (user) 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 (backup) d liu tp trung. D liu c lu tr ri rc trn tng trm.M hnh mng khch ch (Client Server Network / Server Based Network)[sa|sa m ngun]Bi chi tit:Client-serverMng khch ch 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 .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.M hnh qun l mng[sa|sa m ngun]M hnh mng Workgroup[sa|sa m ngun]M hnh mng Workgroup l mt nhm my tnh mng cng chia s ti nguyn nh file d liu, my in. N l mt nhm lgc ca cc my tnh m tt c chng c cng tn nhm. C th c nhiu nhm lm vic (workgroups) khc nhau cng kt ni trn mt mng cc b (LAN).M hnh mng Workgroup cng c coi l mng peer-to-peer bi v tt c cc my trong workgroup c quyn chia s ti nguyn nh nhau m khng cn s ch nh ca Server. Mi my tnh trong nhm t bo tr, bo mt c s d liu cc b ca n. iu ny c ngha l, tt c s qun tr v ti khon ngi dng, bo mt cho ngun ti nguyn chia s khng c tp trung ha. Bn c th kt ni ti mt nhm tn ti hoc khi to mt nhm mi.u im l Workgroups khng yu cu my tnh chy trn h iu hnh Windows Server tp trung ha thng tin bo mt; workgroups thit k v hin thc n gin v khng yu cu lp k hoch c phm vi rng v qun tr nh domain yu cu; workgroups thun tin i vi nhm c s my tnh t v gn nhau ( 10 my).Nhc im l mi ngi dng phi c mt ti khon ngi dng trn mi my tnh m h mun ng nhp; bt k s thay i ti khon ngi dng, nh l thay i mt khu hoc thm ti khon ngi dng mi, phi c lm trn tt c cc my tnh trong Workgroup, nu bn qun b sung ti khon ngi dng mi ti mt my tnh trong nhm th ngi dng mi s khng th ng nhp vo my tnh v khng th truy xut ti ti nguyn ca my tnh ; vic chia s thit b v file c x l bi cc my tnh ring, v ch cho ngi dng c ti khon trn my tnh c c s dng.M hnh mng Domain[sa|sa m ngun]Bi chi tit:Tn minM hnh mng Domain l mt nhm my tnh mng cng chia s c s d liu th mc tp trung (central directory database). Th mc d liu cha ti khon ngi dng v thng tin bo mt cho ton b Domain. Th mc d liu ny c bit nh l th mc hin hnh (Active Directory).Trong mt Domain, th mc ch tn ti trn cc my tnh c cu hnh nh my iu khin min (domain controller). Mt domain controller l mt Server qun l tt c cc kha cnh bo mt ca Domain. Khng ging nh mng Workgroup, bo mt v qun tr trong domain c tp trung ha. c Domain controller, nhng my ch (server) phi chy dch v lm Domain controller (dch v c tch hp sn trn cc phin bn Windows Server ca Microsoft; hoc trn Linux, ta cu hnh dch v Samba lm nhim v Domain controller,...).Mt domain khng c xem nh mt v tr n hoc cu hnh mng ring bit. Cc my tnh trong cng domain c th trn mt mng LAN hoc WAN. Chng c th giao tip vi nhau qua bt k kt ni vt l no, nh: Dial-up, Integrated Services Digital Network (ISDN), Ethernet, Token Ring, Frame Relay, Satellite, Fibre Channel.u im l cho php qun tr tp trung. Nu ngi dng thay i mt khu ca h, th s thay s c cp nht t ng trn ton Domain; Domain cung cp quy trnh ng nhp n gin ngi dng truy xut cc ti nguyn mng m h c php truy cp; Domain cung cp linh ng ngi qun tr c th khi to mng rt rng ln.Cc min in hnh trong Windows Server c th cha cc kiu my tnh sau: My iu khin min (Domain controllers) lu tr v bo tr bn sao th mc. Trong domain, ti khon ngi dng c to mt ln, Windows Server ghi n trong th mc ny. Khi ngi dng ng nhp ti my tnh trong domain, domain controller kim tra th mc nh tn ngi s dng, mt khu v gii hn ng nhp. Khi c nhiu domain controllers, chng nh k ti to thng tin th mc ca chng. Cc my ch thnh vin (Member servers): Mt my member server l mt my ch m khng c cu hnh nh l domain controller. My ch khng lu tr thng tin th mc v khng th xc nhn domain ngi dng. Cc my ch c th cung cp cc ti nguyn chia s nh cc th mc dng chung hay cc my in. Cc my tnh trm (Client computers): Cc my tnh trm chy mt h iu hnh dng cho my trm ca ngi dng v cho php ngi dng truy cp ti ngun ti nguyn trong domain.Khng ging nh Workgroup, Domain phi tn ti trc khi ngi dng tham gia vo n. Vic tham gia vo Domain lun yu cu ngi qun tr Domain cung cp ti khon cho my tnh ca ngi dng ti domain . Tuy nhin, nu ngi qun tr cho ngi dng ng c quyn, ngi dng c th khi to ti khon my tnh ca mnh trong qu trnh ci t.Thng s mng[sa|sa m ngun]Bng thng (Bandwidth - B)[sa|sa m ngun]Bng thng l rng di tn, tc chnh lch gia tn s cao nht vi tn s thp nht trn cng mt knh truyn thng hay gia cc bc sng.Trong cng ngh my tnh, bandwidth vi ngha l bng thng thng c dng ch mt khi lng d liu c th truyn ti c trong mt thi gian nht nh. i vi cc thit b k thut s, bng thng c tnh vi n v bps (bit mi giy) hay Bps (byte mi giy). Cn i vi cc thit b analog, bng thng c th hin bng chu k mi giy, hay Hertz (Hz).Bng thng l o lng mc thng tin hay bit c th chy t ni ny sang ni khc trong mt khong thi gian cho trc tnh theo giy. tr (Latency - L)[sa|sa m ngun] tr l khong thi gian chuyn mt thng ip t nt ny n nt khc trong h thng mng.Thng lng (Throughput T)[sa|sa m ngun]Thng lng l lng d liu i qua ng truyn trong mt n v thi gian. Hay thng lng l bng thng thc s m cc ng dng mng c s dng trong mt thi gian c th (thng lng c th c bin i theo thi gian).Thng lng thng nh hn nhiu so vi bng thng ti a c th c ca mi trng truyn dn c s dng (Throughput Bandwidth).Thng lng ca mng my tnh ph thuc vo cc yu t nh khong cch lin kt, mi trng truyn dn, cc cng ngh mng, dng d liu c truyn, s lng ngi dng trn mng, my tnh ngi dng, my ch, Cc phng php truyn thng d liu[sa|sa m ngun]Bi chi tit:Nt mng Phng thc unicast: Mt nt ngun mun gi mt thng ip n duy nht mt nt ch trn h thng mng. Phng thc multicast: Mt nt ngun mun gi mt thng ip n mt nhm cc nt ch trn h thng mng. Phng thc broadcast: Mt nt ngun mun gi mt thng ip n tt c cc nt ch khc trn h thng mng.Giao thc mng[sa|sa m ngun]Bi chi tit:Giao thc truyn thngBi chi tit:TCP/IPCc m hnh mng in hnh[sa|sa m ngun]Cc m hnh di y,TCP/IPvOSIl cc tiu chun, khng phi l cc b lc hay phn mm to giao thc.OSI[sa|sa m ngun]

M hnh OSI vi by tng.OSI, hay cn gi l "M hnh lin kt gia cc h thng m", l thit k da trn s pht trin caISO(T Chc Tiu Chun Quc T). M hnh bao gm 7 tng:1. Tng ng dng: cho php ngi dng (con ngi hay phn mm) truy cp vo mng bng cch cung cp giao din ngi dng, h tr cc dch v nh gi th in t truy cp v truyn file t xa, qun l CSDL dng chung v mt s dch v khc v thng tin.2. Tng trnh din: thc hin cc nhim v lin quan n c php v ni dung ca thng tin gi i.3. Tng phin: ng vai tr "kim sot vin" hi thoi (dialog) ca mng vi nhim v thit lp, duy tr v ng b ha tnh lin tc gia hai bn.4. Tng giao vn: nhn d liu t tng phin, ct chng thnh nhng n v nh nu cn, gi chng xung tng mng v kim tra rng cc n v ny n c u nhn.5. Tng mng: iu khin vn hnh ca mng con. Xc nh m u v kt thc ca mt cuc truyn d liu.6. Tng lin kt d liu: nhim v chnh l chuyn dng ca d liu thnh cc khung d liu (data frames) theo cc thut ton nhm mc ch pht hin, iu chnh v gii quyt cc vn nh h, mt v trng lp cc khung d liu.7. Tng vt l: Thc hin cc chc nng cn thit truyn lung d liu di dngbiti qua cc mi trng vt l.TCP/IP[sa|sa m ngun]TCP/IPcng ging nhOSInhng kiu ny c t hn ba tng:1. Tng ng dng: bao gm nhiu giao thc cp cao. Trc y ngi ta s dng cc p dng u cui o nhTELNET,FTP,SMTP. Sau nhiu giao thc c nh ngha thm vo nhDNS,HTTP...2. Tng giao vn: nhim v ging nh phn giao vn ca OSI nhng c hai giao thc c dng ti lTCPvUDP.3. Tng mng: chu trch nhim chuyn gi d liu t ni gi n ni nhn, gi d liu c th phi i qua nhiu mng (cc chng trung gian). Tng lin kt d liu thc hin truyn gi d liu gia hai thit b trong cng mt mng, cn tng mng m bo rng gi d liu s c chuyn t ni gi n ng ni nhn. Tng ny nh ngha mt dng thc ca gi v ca giao thc lIP.4. Tng lin kt d liu: S dng truyn gi d liu trn mt mi trng vt l.Thit b mng[sa|sa m ngun]Thit b truyn dn[sa|sa m ngun] Cp xon i (Twisted pair cable): Cp xon i gm nhiu cp dy ng xon li vi nhau nhm chng pht x nhiu in t. Do gi thnh thp nn cp xon c dng rt rng ri. C hai loi cp xon i c s dng rng ri trong LAN l loi c v bc chng nhiu v loi khng c v bc chng nhiu. Cp ng trc(Coaxial Cable) Cp si quang(Fiber optic cable): l mt loi cp vin thng lm bng thy tinh hoc nha, s dng nh sng truyn tn hiu. Cp quang di, mng thnh phn ca thy tinh trong sut bng ng knh ca mt si tc. Chng c sp xp trong b c gi l cp quang v c s dng truyn tn hiu trong khong cch rt xa. Khng ging nh cp ng truyn tn hiu bng in, cp quang t b nhiu, tc cao v truyn xa hn.Thit b kt ni[sa|sa m ngun] Wireless Access Point l thit b kt ni mng khng dy c thit k theo chun IEEE 802.11b, cho php ni LAN to LAN, dng c ch CSMA/CA gii quyt tranh chp, dng c hai kin trc kt ni mng l Infrastructure v AdHoc, m ha theo 64/128 bit. N cn h tr tc truyn khng dy ln ti 11Mbps trn bng tn 2,4GHz v dng cng ngh radio DSSS (Direct Sequence Spectrum Spreading). Wireless Ethernet Bridge l thit b cho php cc thit b Ethernet kt ni vo mng khng dy. V d nh thit b Linksys WET54G Wireless-G Ethernet Bridge. N h tr bt k thit b Ethernet no kt ni vo mng khng dy d thit b Ethernet c th l mt thit b n hoc mt router kt ni n nhiu thit b khc. Cc mngl mt loi card m rng c gn thm trn my tnh, cung cp giao tip vt l v logic gia my tnh vi cc thit b mng, h thng mng thng qua phng tin truyn dn. Repeatern gin ch l mt b khuch i tn hiu gia hai cng ca hai phn on mng. Repeater c dng trong m hnh mng Bus nhm m rng khong cch ti a trn mt ng cp. C hai loi Repeater ang c s dng l Repeater in v Repeater in quang. Dng ni hai mng c cng giao thc truyn thng Hubl thit b c chc nng ging nh Repeater nhng nhiu cng giao tip hn cho php nhiu thit b mng kt ni tp trung vi nhau ti mt im. Hub thng thng c t 4 n 24 cng giao tip, thng s dng trong nhng mng Ethernet 10BaseT. Tht ra, Hub chi l Repeater nhiu cng. Hub lp li bt k tn hiu no nhn c t mt cng bt k v gi tn hiu n tt c cc cng cn li trn n. Hub hot ng lp vt l ca m hnh OSI v cng khng lc c d liu. Hub thng c dng ni mng, thng qua nhng u cm ca n ngi ta lin kt vi cc my tnh di dng hnh sao. Hub c chia lm hai loi chnh: Hub th ng (Passive hub) v Hub ch ng (Active hub). Bridgel thit b cho php ni kt hai nhnh mng, c chc nng chuyn c chn lc cc gi tin n nhnh mng cha my nhn gi tin. lc cc gi tin v bit c gi tin no thuc nhnh mng no th Bridge phi cha bng a ch MAC. Bng a ch ny c th c khi to t ng hay phi cu hnh bng tay. Do Bridge hiu uc a ch MAC nn Bridge hot ng tng hai (tng data link) trong m hnh OSI. Modeml thit b dng chuyn i d liu nh dng s thnh d liu nh dng tng t cho mt qu trnh truyn t mi trng tn hiu s qua mi trng tn hiu tng t v sau tr mi trng tn hiu s pha nhn cui cng. Tn gi Modem tht ra l t vit tt c ghp bi nhng ch ci u tin ca MOdulator/DEModulator B iu bin/B gii iu bin. Switchl s kt hp hi ha v k thut gia Bridge v Hub. C ch hot ng ca Switch rt ging Hub bi v l thit b tp trung cc kt ni mng li trn n. Nhng cng giao tip trn Switch l nhng Bridge thu nh c xy dng trn mi cng giao tip tng ng. Routerl b nh tuyn dng ni kt nhiu phn on mng, hay nhiu kiu mng (thng l khng ng nht v kin trc v cng ngh) vo trong cng mt mng tng tc. Thng thng c mt b x l, b nh, v hai hay nhiu cng giao tip ra/vo. Brouter Gatewayl thit b trung gian dng ni kt nhng mng khc nhau c v kin trc ln mi trng mng. Gateway c hiu nh cng ra vo chnh ca mt mng ni b bn trong kt ni vi mng khc bn ngoi. C th l thit b phn cng chuyn dng nhng thng l mt server cung cp kt ni cho cc my m n qun l i ra bn ngoi giao tip vi mt mng khc.

The Ten Commandments[edit]1. Thou shalt not use a computer to harm other people.2. Thou shalt not interfere with other people's computer work.3. Thou shalt not snoop around in other people's computer files.4. Thou shalt not use a computer to steal.5. Thou shalt not use a computer to bear false witness6. Thou shalt not copy or use proprietary software for which you have not paid.7. Thou shalt not use other people's computer resources without authorization or proper compensation.8. Thou shalt not appropriate other people's intellectual output.9. Thou shalt think about the social consequences of the program you are writing or the system you are designing.10. Thou shalt always use a computer in ways that ensure consideration and respect for your fellow humans.11. Mi iu rn[sa]1. Khng s dng mt my tnh lm hi ngi khc.2. Khng can thip vo cng vic my tnh ca ngi khc.3. Khng rnh m xung quanh trong tp tin my tnh ca ngi khc.4. Khng s dng mt my tnh n cp.5. Khng s dng mt my tnh lm chng sai6. Khng sao chp hoc s dng phn mm c quyn m bn khng tr.7. Khng s dng ti nguyn my tnh ca ngi khc m khng c php hoc n b hp l.8. Khng thch hp u ra tr tu ca ngi khc.9. ng ngh v nhng hu qu x hi ca chng trnh bn ang vit hoc h thng bn ang thit k.10. ng lun lun s dng mt my tnh theo cch m bo xem xt v tn trng i vi con ngi ng bo ca bn.Ch gii[sa] Rn: 1n gin ch cn t: Khng s dng mt my tnh trong nhng cch c th gy tn hi cho ngi khc.Gii thch: rn ny ni rng n l phi o c s dng mt my tnh lm hi ngi khc.N khng phi l hn ch chn thng vt l.N bao gm lm hi hoc lm h hng d liu hoc cc tp tin ca ngi dng khc.Cc trng thi rn rng l sai s dng mt my tnh n cp thng tin c nhn ca mt ai .Thao tc hoc xa cc tp tin ca ngi dng khc l o c sai.N l phi o c vit chng trnh, m trn thc hin dn n trm cp, sao chp hoc sau khi c truy cp tri php vo d liu ca ngi dng khc.c tham gia trong cc hot ng nh hack, spam, phishing hay bt nt trn mng khng ph hp vi o c my tnh. Rn 2n gin ch cn t: Khng s dng cng ngh my tnh gy nhiu trong cng vic ca ngi dng khc.Gii thch: Phn mm my tnh c th c s dng theo cch lm phin ngi khc hoc lm gin on cng vic ca h.Virus, v d, l nhng chng trnh c ngha l gy tn hi cho cc chng trnh my tnh hu ch hay can thip vo hot ng bnh thng ca mt my tnh.Phn mm c hi c th lm gin on cc hot ng ca my tnh theo nhng cch nhiu hn mt.N c th qu ti b nh my tnh thng qua tiu th qu mc cc ngun ti nguyn my tnh, do lm chm hot ng ca n.N c th gy ra mt my tnh hot ng sai hoc thm ch ngng lm vic.S dng phn mm c hi tn cng mt my tnh l phi o c. Rn 3n gin ch cn t: ng do thm d liu my tnh ca ngi khc.Gii thch: Chng ti bit l sai c th c nhn ca mt ai .Trn ng cng, l sai c cc tin nhn email ca ngi khc hoc cc tp tin.Ly d liu t cc tp tin ring t ca ngi khc l khng c g t hn so vi t nhp vo phng ca mt ai .Rnh m trong cc tp tin ca ngi khc hoc c tin nhn c nhn ca ngi khc l xm phm i t ca mnh.C ngoi l ny.V d, gin ip l cn thit v khng th c gi l phi o c khi n c thc hin khng b s dng bt hp php ca cc my tnh.V d, c quan tnh bo lm vic trn cc trng hp ti phm mng cn do thm cc hot ng Internet ca nghi phm. Rn 4n gin ch cn t: Khng s dng cng ngh my tnh n cp thng tin.Gii thch: n cp thng tin nhy cm hoc b r r thng tin b mt l tt nh n cp. l sai lm c c thng tin c nhn ca ngi lao ng t mt c s d liu ca nhn vin hoc c tin s bnh nhn t mt c s d liu ca bnh vin hoc cc thng tin khc nh vy m l c ngha l c gi kn.Tng t nh vy, t nhp vo mt ti khon ngn hng thu thp thng tin v ti khon hoc chim gi l sai.Chuyn tin in t bt hp php ca ngun vn ny l mt loi gian ln.Vi vic s dng cng ngh, nh cp thng tin d dng hn nhiu.My tnh c th c s dng lu tr cc thng tin b nh cp. Rn 5n gin ch cn t: ng ng gp vo s lan truyn thng tin sai lc bng cch s dng cng ngh my tnh.Gii thch: Spread ca thng tin tr thnh virus ngy nay, v Internet.iu ny cng c ngha l tin tc sai hay tin n c th ly lan nhanh chng thng qua cc trang web mng x hi hoc email.c tham gia trong lu thng thng tin khng chnh xc l v o c.Mail v pop-up thng c s dng truyn b thng tin sai hoc cung cp cho cc cnh bo sai vi mc ch duy nht ca vic bn sn phm.Mail t cc ngun khng tin cy qung co sn phm nht nh hoc lan rng mt s thng tin kh tin, khng phi l him.Tham gia trc tip hoc gin tip trong lu thng thng tin sai lch v mt o c l sai. Rn 6n gin ch cn t: Khng c sao chp phn mm hoc mua bn lu.Tr tin cho phn mm tr khi n l min ph.Gii thch: Ging nh bt k tc phm ngh thut hay vn hc khc, phn mm c bn quyn.Mt on m l tc phm gc ca c nhn ngi to ra n.N l bn quyn trong tn ca mnh.Trong trng hp ca mt phn mm vn bn pht trin cho cc t chc, ng lm vic cho t chc nm gi bn quyn cho n.Copyright ng tr khi tc gi ca n khng phi l b n.Ly bn sao bt hp php ca phn mm c bn quyn l phi o c. Rn 7n gin ch cn t: Khng s dng ti nguyn my tnh ca ngi khc tr khi c y quyn.Gii thch: Nhiu ngi s dng cc h thng c s dng c th cc mt khu.t nhp vo mt khu ca mt s ngi dng khc, do xm nhp khng gian ring t ca mnh l v o c.N khng phi l o c hack mt khu t c quyn truy cp tri php vo h thng my tnh c bo v bng mt khu.Truy cp d liu m bn khng c quyn truy cp hoc t c quyn truy cp vo my tnh ca ngi dng khc m khng c s cho php ca ng khng phi l o c. Rn 8n gin ch cn t: l sai khng nh ch quyn trn mt tc phm m l sn phm ca tr tu ca ngi khc.Gii thch: Chng trnh c pht trin bi mt nh pht trin phn mm l ti sn ca c / anh.Nu anh ta ang lm vic vi mt t chc, h l ti sn ca t chc.Sao chp chng v tuyn truyn cho h trong tn ring ca mt ngi l phi o c.iu ny p dng cho bt k cng vic sng to, chng trnh hoc thit k.Thit lp quyn s hu trn mt tc phm m khng phi ca mnh l c o c sai. Rn 9n gin ch cn t: Trc khi pht trin mt phn mm, suy ngh v cc tc ng x hi, n c th c.Gii thch: Nhn vo nhng hu qu x hi m mt chng trnh c th c, m t mt ci nhn rng hn nhn vo cng ngh.Mt phn mm my tnh trn pht hnh, t n hng triu.Phn mm nh tr chi video v hnh nh ng hoc phn mm gio dc c th c mt tc ng x hi v ngi dng ca h.Khi lm vic trn b phim hot hnh hay thit k tr chi video, v d, l cc lp trnh vin c trch nhim hiu i tng / ngi s dng ca mnh v nh hng ca n c th c trn chng.V d, mt tr chi my tnh cho tr em khng nn c ni dung c th gy nh hng tiu cc n h.Tng t nh vy, vit phn mm c hi l c o c sai.Mt phn mm pht trin cng ty / pht trin nn xem xt cc nh hng c th c m s ca h i vi x hi ni chung. 10 iu rnn gin ch cn t: Khi s dng my tnh lin lc, c tn trng v lch s vi cc thnh vin khc.Gii thch: Cc nghi thc giao tip, chng ti lm theo trong th gii thc c p dng giao tip trn my tnh l tt.Trong khi giao tip qua Internet, ta nn i x vi nhng ngi khc tn trng.Mt khng nn xen vo can thip khng gian ring t ca ngi khc, s dng ngn ng lng m, lm bo co sai hoc vt qua nhng nhn xt v trch nhim v nhng ngi khc.Mt nn lch s khi giao tip qua cc trang web v nn tn trng thi gian v ngun lc ca ngi khc.Ngoi ra, ngi ta phi n cn vi mt ngi dng my tnh mi lm quen.