Exam NSE7_FSN_AR-7.6 Topic 1 Question 108 Discussion

The correct answers are A and C .
The exhibit shows that preserve-session-route is enabled on port1:
config system interface
edit " port1 "
set preserve-session-route enable
next
end
The study guide explains the effect of this setting exactly:
"enable: FortiGate marks existing session routing information as persistent, and applies only the modified routes to new sessions" It also states:
"The current route must still be present in the FIB. Otherwise, FortiGate flags the session as dirty and reevaluates it" And the same page further clarifies:
"If you enable this setting, sessions passing through that interface continue to pass without being affected by the routing changes. The routing changes apply only to new sessions. If the route is removed from the FIB, then FortiGate must flag the session as dirty, flush its gateway information, and reevaluate the session." This proves:
* A is correct because with preserve-session-route enable, existing sessions are normally preserved and routing changes apply only to new sessions.
* C is correct because the session remains unchanged unless the current route is removed from the FIB
/routing table, in which case FortiGate dirties and reevaluates the session.
Why the other options are wrong:
* B is wrong because when the active route is removed, FortiGate does not simply mark the session dirty and stop there. The study guide says it "flags the session as dirty and reevaluates it" , which means route lookup happens again.
* D is wrong because the session does change if the active route is removed. FortiGate flushes gateway information and reevaluates the session.
So the verified answers are: A, C .