Can a SQL Server Distributed Availability Group be between AGs in different Active Directory Domains?

Question

Three questions please:

• Can we have a single DAG across 3 WSFC clusters i.e. spanning 3 AGs?

• If so, is it possible to configure it such that two AGs are in the same Active Directory domain while a third one is in a different AD domain?

• If configuring a single DAG across 3 AGs is not recommended, is one across two AGs in two different AD domains possible?

Thank you

Answer 1

Can we have a single DAG across 3 WSFC clusters i.e. spanning 3 AGs?

No, each hop requires a Distributed AG. Each Distributed AG can only have two AGs in it as of SQL Server 2022. This is somewhat called out in the documentation via the pictures.

is it possible to configure it such that two AGs are in the same Active Directory domain while a third one is in a different AD domain?

You can create Distributed AGs across AD forests, you'll either need to have the proper trusts setup between the forests or you'll be required to use certificate based endpoints.

If configuring a single DAG across 3 AGs is not recommended, is one across two AGs in two different AD domains possible?

See the first and second answers.

• PTL_SQL: thank you so much again! :-) Yes, I did go through that documentation and most of what you have said was my understanding as well, however, I just needed a confirmation of my understanding from an expert like you. I am very appreciative.