Do I have to have a standy by IP address bound to every interface. Right now some of my interfaces have stand by IP address assigned to them and some don't. It does not appear to make a diffrence on how the firewall performs. I understand you need a standby IP address if you plan to monitor both firewall nodes. But that would only be required on the managment interface. I have read the configuration guide and it states the stand by IP address must be in the same subnet. But it does not say if it is optional or not, Yet the ASDM allows you to configure the firewall in failover mode without a stand by IP address. I figure the ASDM would be enforcing the standby IP address requirement if it was a must. So what is the advantages/disadvantages
My best guess is:
The standby IP address is used to monitor the health of the interface. It is used for the PING test during the health check proccess.
Yes, you should have a standby address on every interface that's in use. As you've guessed, this address *is* used to monitor the health of the interface, so if you don't have it on some interfaces you don't really have full failover functionality.