TCP Flags

Question 1

What is S?

Answer 1

SYN (Synchronise) - used during session setup to agree on initial sequence numbers. Sequence numbers are random.

Question 2

What is F?

Answer 2

FIN (Finish) - used during a graceful session close to show that the sender has no more data to send.

Question 3

What is R?

Answer 3

RST (Reset) - an instantaneous abort in both directions (abnormal session disconnection).

Question 4

What is P?

Answer 4

PSH (Push) - forces data delivery without waiting for buffers to fill. Used for interactive traffic. Data will also be delivered to the application on the receiving end without buffering.

Question 5

What is U?

Answer 5

URG (Urgent) - data is sent out of band.

Question 6

What are the TCP flags?

Answer 6

A - ACK (acknowledge)
S - SYN (synchronise)
F - FIN (finish)
R - RST (reset)
P - PSH (push)
U - URG (urgent)

Question 7

What is A?

Answer 7

ACK (Acknowledge) - the receiver will send an ACK that equals the senders sequence number plus the amount of data (Len) at the TCP layer.