Question: How NetScaler terminates the TCP session with client idle timeout 

Answer: NetScaler considers the following timeout values :

Client idle Timeout: Idle time, in seconds, after which a client connection is terminated.
 
ZOMBIE Timeout: zombie process runs at the set timeout interval and clean-up session that are idle. 
So, when zombie parameter is set to 120: the process deletes session idle since more than idle timeout seconds. 
 
If the client Idle timeout value is set to 60 Sec and Zombie timeout is set to default 120 Sec the session cleanup occurs after 60 Sec during the zombie interval.

The following tests were carried out in the Lab :

Synopsys

set ns timeout [-zombie <positive_integer>] [-httpClient <positive_integer>] [-httpServer <positive_integer>] [-tcpClient <positive_integer>] [-tcpServer <positive_integer>] [-anyClient <positive_integer>] [-anyServer <positive_integer>] [-halfclose <positive_integer>] [-nontcpZombie <positive_integer>] [-ReducedFinTimeOut <positive_integer>] [-ReducedRstTimeOut <positive_integer>] [-NewConnIdleTimeOut <positive_integer>]