1,525 views

The persist timer is used in TCP to

1. To detect crashes from the other end of the connection
2. To enable retransmission
4. To timeout FIN_Wait$1$ condition

### Subscribe to GO Classes for GATE CSE 2022

$\underline{\textbf{Answer:}\Rightarrow}\;\mathbf{c.}$

The persist timer is used for protecting the TCP from being in a deadlock situation that could occur if the following window size update from the receiver is lost, and the sender is not able to send more data until it receives a new window size update from the receiver.
by
21 48 118

To deal with a zero-window-size deadlock situation, TCP uses a persistence timer. When the sending TCP receives an acknowledgment with a window size of zero, it starts a persistence timer. When the persistence timer goes off, the sending TCP sends a special segment called a probe. This segment contains only 1 byte of new data. It has a sequence number, but its sequence number is never acknowledged; it is even ignored in calculating the sequence number for the rest of the data. The probe causes the receiving TCP to resend the acknowledgment which was lost.
by
74 181 300

Persistent Timer – To deal with a zero-window-size deadlock situation, TCP uses a persistence timer.When the sending TCP receives an acknowledgment with a window size of zero, it starts a persistence timer. When the persistence timer goes off, the sending TCP sends a special segment called a probe. This segment contains only 1 byte of new data. It has a sequence number, but its sequence number is never acknowledged; it is even ignored in calculating the sequence number for the rest of the data. The probe causes the receiving TCP to resend the acknowledgment which was lost.

So C is correct.

by
27 61 153

1
1,682 views