Listener IP address offline I have an availability group on SQL Server 2016 SP1 CU5 on Windows 2012 R2.
It works fine, but I need to add an IP address on another network.

So I added the IP:

ALTER AVAILABILITY GROUP [AG_MOON]
MODIFY LISTENER N'AGLISTMOON'
(ADD IP (N'10.20.2.102', N'255.255.255.0')
);


The command runs successfully. Then I query the view: sys.availability_group_listener_ip_addresses:

SELECT * FROM sys.availability_group_listener_ip_addresses;


I can see both addresses, but the old address is in state 1 (ONLINE). The new address is OFFLINE.

There are no errors or other indications of a problem in the error log.

How can I set it ONLINE?
There can only be one IP address online for the listener at a given time.  Both IP addresses are registered in DNS (by default) even though one is offline, and when a client looks up the address of the listener, it will get two addresses.  If the client is "multi-subnet failover aware," it will try both addresses and use the one that responds

If the client is not "multi-subnet failover aware," it may try to use the IP address that is offline, and accordingly will fail to connect.  So if you start having intermittent client connection failures, this is why.

To have it only register the IP address that is online, change the RegisterAllProvidersIp setting on the listeners network name resource to 0.  See Multi-subnet Clustered SQL + RegisterAllProvidersIP + SharePoint 2013