Hello,
So there are a lot of things that can cause a zone transfer to fail.
1. you haven’t enabled zone transfer.
2. the connection between the two appliances is broken.
3. If using a secure transfer, the Key may not be correct and not accepted.
4. Starting a transfer on a HA fail-over.
5. NTP settings are off. (This can happen a lot if you are using a secured transfer.)
6. If a Member that might have been failed over to is on another network from its partner and you enabled zone transfer for specific networks.
There are more things than just this but hopefully this helps get you started.
Thank you,
Kevin Zettel
3474 
1
