Need help with GTM upgradation

The answer is already there in devcentral... 🙂

Once the GTMs in a sync group have been upgraded, there might be issues with the Sync Groups. You can circumvent by naming the SYNC group name to something else and renaming back to the original sync group name after the upgrades.

Say you have two GTMs (GTM1 and GTM2) in your sync group with syncgroup name as GTMSYNC.

Backup GTM configs
GTM1 - Rename SYNC Group name to GTMSYNC-Other1
GTM1 - Install V11 on a new volume and reboot to new V11 volume. Test DNS functionality by testing against GTM1.
GTM2 - Rename SYNC Group name to GTMSYNC-Other2
GTM2 - Install V11 on a new volume and reboot to new V11 volume. Test DNS functionality by testing against GTM2.
GTM1 and GTM2 - Rename SYNC Group name back to GTMSYNC
Perform iqdump from each GTM to the other GTM to verify iQuery. Also perform iqdump from GTM to all the LTMs that they are talking to, to verify iQuery is still working.
if iQuery is failing against the LTMs, perform bigip_add against the LTMs to re-establish iQuery connectivity.
On another note keep away from versions such as V11.3.0 HF7 and V11.4.0 HF3, etc because of a BIND vulnerability that it introduces. The downloads page has the warning in there, so avoid such releases.

"Customers that rely on BIND Zone syncing to replicate their DNS database between GTMs should not upgrade to this HF due to a problem with Zone syncing. This issue is being tracked as ID429127."

-Jinshu