Using Distributed Network Names with Availability Groups

I’ve been asked this question a few times, so I feel it’s worth writing about, which is, “Are Distributed Network Names (DNN) supported for SQL Server?”.

The short version is, it’s not supported. The long version is, it’s not supported, but if you’re using a vanilla AG (not distributed) and aren’t using things like replication or filestream, then it’ll probably work – but just because it *probably* works in most cases (there’s always some super niche setup with crazy routing and intermediary appliances that break stuff) doesn’t mean it’s supported or that it’ll always work.

This is the time you might point out, “But Sean, it says it’s supported for FCI’s in 2019 CU2!” and you’d be correct. Good thing I made the title reflective of Availability Groups and not FCI’s, although this is extremely useful, in my opinion, for those running SQL Server in Azure.

There are various scenarios where the current way that AG’s work is not conducive to how DNN’s work, but I’m sure that’ll eventually come around as an improvement much like they have for FCI’s!

Edit: Support was added for AG’s in 2019 CU8, however not all scenarios are supported and will work. Check the documentation for updates and scenarios. It still stands, if you’re not on Azure then there is no reason to use this.