Symptoms
For BIG-IQ with DCD clusters are configured with auto-failover and the active, secondary, and DCD clusters have a network configuration similar to:
Mgmt: 10.145.x.x
Self IP: 10.3.x.x (subnet to talk to BIG IPs)
Discovery address: 10.5.x.x (could be a Gateway address)
The self IP is the subnet BIG-IQ uses to communicate with managed BIG-IP devices, so you must discover a DCD using the self IP. (Discovery/Listeners address)
This IP address is displayed from BIG-IQ and not well-formed because they are in a different subnet (10.3.x.x virtual server 10.5.x.x).
Impact
Unable to form auto failover high availability (HA) as the addresses are not in the same subnet/ because of the "is DCD attached to primary" validation.
Conditions
When the BIG-IQ Quorum for an auto-failover configuration's discovery address is different than the IP address used for the Discovery/listener's address when adding a DCD to BIG-IQ.
Workaround
Create an additional DCD that is in an isolated zone to ensure that it will not be assigned to a BIG-IP not in that zone.
Do not use an API to work around this, as BIG-IQ will return an error because there is a backend validation that compares the DCD cluster you added to the IP addresses of the Quorum.
