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301b Exam - Question 121

While investigating the cause of a device failover, an LTM Specialist discovers the following events in /var/log/ltm:

01010029:5: Clock advanced by 518 ticks

01010029:5: Clock advanced by 505 ticks

01010029:5: Clock advanced by 590 ticks

01010029:5: Clock advanced by 568 ticks

01010029:5: Clock advanced by 1681 ticks

01010029:5: Clock advanced by 6584 ticks

01140029:5: HA daemon_heartbeat tmm fails action is failover and restart.

010c0026:5: Failover condition, active attempting to go standby.

Which issue caused the failover?

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Correct Answer: B

The failover was caused by TMM being descheduled. The log entries mentioning the clock advancing by various ticks indicate that the TMM process was not running for those periods. Consequently, TMM failed to update its heartbeat signal. As the HA daemon relies on these heartbeats to monitor the health of the system, missing heartbeats led the HA daemon to trigger the failover and restart action.

Discussion

3 comments
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WassuOption: A
Oct 12, 2020

Why not A , click bits is ntp related

GVKD
Feb 12, 2024

I think it is B because the NTP being out of sync did not directly cause the Failover, that was caused by the TMM daemon timer falling behind the system time and registering missing the heartbeats due to the forward jump in time when the daemon aligns itself with the system clock again.

DegenhardtOption: A
Nov 11, 2020

https://support.f5.com/csp/article/K10095#anchor2

GVKDOption: B
Feb 12, 2024

B - Correct TMM failed to update its heartbeat signal for over 10 seconds. This event caused the HA daemon to terminate, produce a core file, and cause a failover. https://my.f5.com/manage/s/article/K10095