W4L2 - TCP P2

Question 1

ACK Flag

Answer 1

1 bit

value in acknowledgement field is valid

Question 2

RST Flag

Answer 2

1 bit

reset connection

Question 3

SYN Flag

Answer 3

1 bit

Synchronize sequence numbers used to establish new conenction

Question 4

FIN Flag

Answer 4

1 bit

no more data from sender to transmiter

Question 5

Three Packet Handshake

Answer 5

Client send a SYN package
On receiving, server sends a SYN-ACK package
Client sends back ACK

Question 6

SYN flood

Answer 6

Send many SYN packets with random source ports and spoofed addresses.
The receiver must search a table of existing connections then allocate record when it isn’t found, using lots of CPU

Question 7

Closing a connection

Answer 7

Each side sends FIN to terminate its end of connection

Upon receiving FIN, each side sends ACK

Question 8

RTO

Answer 8

Retransmission timeout

Question 9

Explain how packet loss is handled

Answer 9

RTT - Round Trip Time. When it runs out and if an ACK is not received, then the server will resend. If the Client did get it, then it ACK and the process continues anyway. Vice versa.
Duplicate ACK also implies packet loss. After sender receives 3 duplicate ACK, it ignore RTT expiration and send a packet for each duplicate ACK

Question 10

1 bit

value in acknowledgement field is valid

Answer 10

ACK Flag

Question 11

1 bit

reset connection

Answer 11

RST Flag

Question 12

1 bit

Synchronize sequence numbers used to establish new connection

Answer 12

SYN Flag

Question 13

1 bit

no more data from sender to transmitter

Answer 13

FIN Flag