Exam 301b topic 1 question 121 discussion

Actual exam question from F5's 301b

Question #: 121
Topic #: 1

An active/standby pair of LTM devices deployed with network failover are working as desired. After external personnel perform maintenance on the network, the
LTM devices are active/active rather than active/standby. No changes were made on the LTM devices during the network maintenance.
Which two actions would help determine the cause of the malfunction? (Choose two.)

A. checking that the configurations are synchronized
B. checking the configuration of the VLAN used for failover
C. checking the configuration of the VLAN used for mirroring
D. checking the open ports in firewalls between the LTM devices
E. checking synchronization of system clocks among the network devices

Show Suggested Answer

Suggested Answer: BD 🗳️

by SimonR2 at Aug. 10, 2021, 2:22 p.m.

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Michellangelo

3 months, 2 weeks ago

Selected Answer: BD

The most probable reason for them to go active/active is the devices loose communication. This can because of firewall blocking or VLAN issues. D is best answer. B is second best. Checking the vlan config. It does not say check the vlan config on the LTM device. Just check the vlan config, so by that it could mean check the switch or whatever device. So rules out the point of saying nothing was changed on the LTM device.

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4c2f7ad

4 months, 4 weeks ago

Selected Answer: DE

Does not seem B to be correct. 1. Devices were working as expected 2. no changes has been made to the bigips 3. only external changes took place DE looks more valid

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GVKD

10 months, 1 week ago

BD - Correct

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Kowalsky

3 years, 4 months ago

@SimonR2 I think BD is correct, because B : if you use a VLAN to create your device trust, if the VLAN is splitted, each F5 will not be able to reach the other F5 and will then be active/active D : Same, if the device trust is going through a Firewall (never seen this in prod...) and someone block the port used to do the failover, each F5 will go active too.

upvoted 3 times

SimonR2

3 years, 3 months ago

Yeah you are right, for some reason i read them as internal/external vlans. If they have made changes on the switch which affect the HA VLAN then we would almost certainly see it go active-active.

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SimonR2

3 years, 4 months ago

I believe the correct answer here is DE. Specifically because it says no changes were made on the f5 devices, only on the external equipment. If the devices have gone active active then they may have lost communication with each other or their time may now be out of sync.

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