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Question 1

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Kateri paketi v datoteki tcp_ssh.cap vsebujejo trosmerno rokovanje?

Which of the packets in tcp_ssh.cap are a part of the three-way handshake?

Question 1 Select one:
a.

1, 2, 3, 171, 173

b.

1, 2, 3, 171, 172

c.

1, 2, 3, 171, 172, 173, 174

d.

1, 2, 4

e.

1, 2, 3

Question 2

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Kaj se bo zgodilo z velikostjo zamašitvenega okna (cwin), če pošiljatelj prejme 4 potrditve istega segmenta?

How does the size of the congestion window (cwin) change after the sender has recieved 4 acknowledgements of the same segment?

Question 2 Select one:
a.

cwnd = cwnd + 1*MSS

b.

cwnd = 2*cwnd

c.

cwnd = rwnd/2

d.

cwnd = cwnd/2 +3

e.

cwnd = cwnd/4

Question 3

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V segmentih SYN, SYN ACK in ACK se uporabniški podatki ponavadi ne nahajajo, vendar pa bi se glede na RFC 793 lahko nahajali tudi tam.

According to RFC 793 user data can reside in three-way handshake segments .

Question 3 Select one:

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V programu Wireshark odprite datoteko tcp_pcattcp_n1.cap. Koliko bajtov se prenese v segmentu številka 10?

Use Wireshark to open tcp_pcattcp_n1.cap. How much data is transferred in segment number 10?

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Polje dolžina v glavi paketa UDP vsebuje samo dolžino podatkov v tem paketu.

The length field in the UDP header contains only the length of the data. 

Question 5 Select one:

Question 6

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Iz časov zajema paketov SYN in SYN ACK lahko izračunamo začetni krožni čas potovanja paketa (RTT oz. Round Trip Time). Kakšen je ta čas v datoteki tcp_ssh.cap?

We can use the capture time of the SYN and SYN ACK packets to determine the starting round trip time (RTT). What is this time int he tcp_ssh.cap file?

Question 6 Select one:
a.

1 s

b.

50 s

c.

0,050 ms

d.

1 ms

e.

50 ms

Question 7

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Protokol UDP ima vgrajene mehanizme za odpravljanje napak in zagotavljanje prenosa.

Data correction and delivery assurance are built into the UDP protocol. 

Question 7 Select one:

Question 8

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Kaj pomeni možnost SACK, ki je nastavljena v nekaterih segmentih TCP?

What is the meaning of the TCP SACK option?

Question 8 Select one:
a.

Možnost SACK pomeni, da lahko pošiljatelj konča povezavo s segmentom RST.

SACK enables the sender to finish the connection with the RST segment.

b.

Možnost SACK omogoča prejemniku, da pošiljatelja obvesti katere segmente je že uspešno prejel. Tako mu bo pošiljatelj poslal le segmente, ki jih prejemnik še nima.

With SACK, the data receiver can inform the sender about all segments that have arrived successfully, so the sender need retransmit only the segments that have actually been lost.

c.

Možnost SACK omogoča, da pošiljatelj sam izbere potrditveno številko.

The SACK option permits the sender to select its own acknowledgement number.

Question 9

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V datoteki tcp_ssh.cap je edini paket, ki nima nastavljene zastavice ACK, paket številka:

The only packet that has ACK set to 0 in tcp_ssh.cap is:

Question 9 Select one:
a.

#171 (paket FIN), ker potrjevanje pri rušenju povezave ni potrebno

#171 (FIN packet), closing a connection does not require acknowledgement

b.

#3 (paket ACK), ker je povezava že vzpostavljena in potrjevanje ni več potrebno

#3 (ACK packet), because the connection is now established and acknowledgements are no longer necessary

c.

#2 (paket SYNACK), ker povezava še ni vzpsotavljena

#1 (SYN ACK packet), because the connection is not yet established

d.

#1 (paket SYN), ker povezava še ni vzpostavljena in ne moremo še ničesar potrditi

#1 (SYN packet), because the connection is not yet established

Question 10

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V programu Wireshark odprite datoteko tcp_pcattcp_n1.cap. Katere pakete potrjuje paket številka 12? Bodite pozorni na predhodne potrditve.

Use Wireshark to open tcp_pcattcp_n1.cap. Which packets does packet no. 12 acknowledge? Do not forget about the previous acknowledgements.

Question 10 Select one:
a.

9, 10

b.

5, 6, 7, 9, 10

c.

5, 6, 7, 8, 9, 10, 11

d.

5, 6, 7, 9, 10, 11

e.

9, 10, 11

Question 11

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V programu Wireshark odprite datoteko tcp_pcattcp_n1.cap. Katere pakete potrjuje paket številka 14? Bodite pozorni na predhodne potrditve.

Use Wireshark to open tcp_pcattcp_n1.cap. Which packets does packet no. 14 acknowledge? Do not forget about the previous acknowledgements.

Question 11 Select one:
a.

11, 13

b.

9, 10, 13

c.

9, 10, 11, 13

d.

13

e.

9, 10

Question 12

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Včasih se zdi, kot da UDP ne prispeva "nič pametnega" k protokolarnem skladu. Zakaj sploh potrebujemo protokol UDP?

It seems that UDP does not add anything important to the protocol stack. Why do we actually need UDP?

Question 12 Select one:
a.

UDP je pomemben, ker omogoča zanesljiv prenos podatkov.

UDP is important because it ensures that the data is delivered without errors.

b.

Protokol UDP doda pojem vrat (port), ki jih uporabimo za povezovanje procesov na odjemalcu in strežniku.

The UDP protocol ads the concept of ports which is required to connect processes on the client and server.

c.

Protokola UDP v resnici ne potrebujemo, v sklad so ga dodali samo zaradi združljivosti s skladom ISO/OSI.

We really don't need the UDP protocol. It's just there for ISO/OSI compliance.

d.

Protokol UDP ima kontrolno vsoto.

The UDP protocol calculates a checksum. 

Question 13

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Protokol UDP ima vgrajene mehanizme za nadzor pretoka in nadzor zamašitev.

Data flow control and network congestion control are an integral part of the UDP protocol.

Question 13 Select one:

Question 14

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Kako veliko bo zamašitveno okno takoj po 4. skupini poslanih segmentov, če prenosi potekajo brez napak in uspešno prejmemo vse potrditve do tega dogodka? Začnemo z 1 MSS.

What is congestion window size right after sending the 4th group of segments, if there are no errors in transmit and we receive all acknowledgments for previous segments?  We start with 1 MSS.

 

Question 14 Select one:
a.

1 MSS

b.

2 MSS

c.

8 MSS

d.

16 MSS

e.

4 MSS

Question 15

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Kakšna je pošiljateljeva (192.168.0.101) dejanska začetna sekvenčna številka v datoteki tcp_ssh.cap?

What is the sender's real starting sequence number in the tcp_ssh.cap file?

Question 15 Select one:
a.

0

b.

c6 a1 4e 5b

c.

c6 a1 4e 5a

d.

1

e.

50 dc 25 5f

Question 16

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Kakšen filter moramo uporabiti v programu Wireshark, da se prikažejo samo segmenti TCP, ki nimajo podatkov?

Which Wireshark filter do we need to use if we want to display only segments without any data?

Question 16 Select one:
a.

tcp.length == 0

b.

tcp.data == 0

c.

tcp.nodata

d.

udp

e.

tcp.len == 0