de thi mmt 2010

thi mn Mng v Truyn thng Hc k I nm hc 2010-2011 Thi gian : 90 pht / 8 trang Ging vin: H Vn Tho

Lu :

- c s dng ti liu + laptop

- Khng c trao i ti liu bng bt c hnh thc no

- Lm bi trn thi

1. Hy gii thch n gin ba dch v ca dch v hng kt ni (Connection Oriented Service)?

Reliable Data Transfer: ...................................................................................

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Flow Control: .......................................................................................................

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Congestion Control: ...........................................................................................

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2. Lit k cc loi delay (tr) xy ra khi mt gi tin di chuyn trn mng:

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H tn :

MSSV :

Ch k gim th :

3. Xt hai my A v B ni vi nhau bng mt ng truyn trc tip vi tc R = 28 (kb/s). Gi s rng hai my ny cch nhau mt khong l d (m), v vn tc truyn dn ca ng truyn l s = 2.5x108 (m/s). My A gi mt gi tin c chiu di L = 100 (bit) cho my B. Hy tm chiu di d sao cho tr dprop = dtrans. (Khng tnh cc tr khc.)

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4. Xt li v d v on xe trong chng 1 phn 4 (xem hnh di). Gi s rng tc di chuyn ca xe l 100 km/h, v trm phi mt 10 s x l 1 xe. Gi s rng khong cch gia cc trm ch l 50 km v on xe c ti 20 chic. Hy tnh tr (end-to-end delay) ca on xe t trm th nht n trc trm th ba:

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5. phn bit mt tin trnh chy trn mt my khc trn mng, chng ta cn phi c nhng thng tin no?

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6. Ti sao cc giao thc HTTP, FTP, SMTP, POP3 chy trn nn ca giao thc TCP thay v UDP?

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7. Gi s Alice dng mt ti khon Webmail ca Google (mail.google.com) gi mt thng ip cho Bob. Bob s dng giao thc IMAP truy cp ti khon email ca mnh ti example.com. Hy v s m t lm cch no thng ip truyn t Alice ti Bob, v ghi r cc giao thc tng ng dng s dng tng giai on.

8. Kt qu sau khi chy mt lnh nslookup nh sau:

Server: BITSY.MIT.EDU Adress: 18.72.0.3 Non-authoritative answer: Name: www.facebook.com Address: 66.220.149.32

Hy tr li cc cu hi sau:

a. DNS server dng tm kim l g?

Name: .....................................................................................................................

a ch IP: ................................................................................................................

b. Ni cn tm kim l g?

Name: .....................................................................................................................

a ch IP: ................................................................................................................

c. Non-authoritative answer c ngha l g?

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9. Gi s mt ngi dng truy cp mt trang web gm c mt on vn bn v 10 hnh. C bao nhiu request HTTP GET c gi t trnh duyt web? Gii thch.

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10. Cho mn hnh Wireshark ca mt thng ip DNS sau:

Hy tr li cc cu hi sau.

a. C bao nhiu trng trong UDP header? Lit k.

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b. Gi tr ca trng Length l 37. ngha ca n l g?

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11. Xt v d v giao thc Telnet trong chng 3 phn 5. Gi s ngi dng t my A g chui Hi (gm 2 k t H v i) gi qua my B. Hy v s biu din qu trnh (ghi r s Seq v ACK) cc thng ip c gi qua li gia A v B. Gi s rng thng ip u tin t A c Seq = 20 v ACK = 40.

12. Cho mn hnh Wireshark ca mt thng ip ICMP sau. Hy tr li cc cu hi:

a ch IP ca my gi? : .......................................................................................

C bao nhiu byte trong IP header? : .................................................................

Kch thc d liu (payload) ca gi tin IP (datagram)? : ..................................

Gi tin ny c b phn mnh hay khng? Gii thch: .............................................

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13. Mt gi tin (datagram) IP c chiu di 3000 byte c gi vo mt ng truyn c MTU l 1000 byte. Gii s gi tin c nh danh (identification number) l 100. Hy xc nh gi tin c phn mnh thnh bao nhiu fragment, v xc nh cc thuc tnh ca n (length, ID, fragflag, offset)?

Hy v cc phn mnh v cc thuc tnh ca n.

14. Cho mng my tnh nh hnh sau, vi chi ph ng i. Hy s dng thut ton Dijkstra tm ng i ngn nht t nt H ti tt c cc nt khc trn mng.

length= 3000

ID= 100

fragflag= 0

offset= 0

a. Trnh by thut ton Dijkstra

Step N D(A),p(A) D(B),p(B) D(C),p(C) D(D),p(D) D(E),p(E) D(F),p(F) D(G),p(G)

b. V cy ngn nht t nh H

c. Kt qu trong forwarding table ca nh H:

Destination Link

Chc cc bn thi tt

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