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Availability Group Listener DNS Response Expand / Collapse
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Posted Wednesday, February 13, 2013 10:06 AM
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I'm trying to understand something about Availability Group listeners that are configured on multiple subnets...
I have an availability group listener with two IP addresses on different subnets. Obviously, only 1 IP is online. If I do an nslookup against the listener name it comes back with both IP addresses as expected. If i ping the listener name, I will get a reply provided it resolves to the IP address that is currently online. If however, it resolves to the other IP address that is not online, it will not reply.
So, this leads me to understand that if I am connecting to an Availability Group via the listener name, and my client is not Multi-Subnet aware, there's a good chance that I will not be able to connect because the request may resolve to the wrong IP address. Is this correct?

Post #1419637
Posted Monday, February 18, 2013 3:17 AM
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I just did a quick read of this:

http://msdn.microsoft.com/en-gb/library/hh213080.aspx#CreateAddiitListener

However if using 2 static IPs of different subnets and you use the listener name in your connection string, then the client you use should resolve the listener name to the correct IP for that subnet and hence you should be connected to your current primary.

Thats how I read it although I could be wrong.
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Posted Tuesday, February 19, 2013 1:50 AM
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Kwisatz78 (2/18/2013)
I just did a quick read of this:

http://msdn.microsoft.com/en-gb/library/hh213080.aspx#CreateAddiitListener

However if using 2 static IPs of different subnets and you use the listener name in your connection string, then the client you use should resolve the listener name to the correct IP for that subnet and hence you should be connected to your current primary.

Thats how I read it although I could be wrong.


Yes but this depends on the client right? If the client does not support multi-subnet failover then I don't think its safe to use the listener name because it does not know that the server could be listening on more than one address. This is what I have found from testing but I just wanted to confirm that this is the expected behavior.
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