Sites and services auto generate

Question

I have 4 sites and 4 domain controllers in my environment (one at each site) and I'm migrating them over to new hardware. I've stood up the new servers, fully patched, enabled Domain Services, etc on the new servers and they are all listed as domain controllers (so I now have 8 total, 2 at each location). In sites and services, each of the new domain controllers have a single connection back to the old domain controller at its site (I've yet to decommission them) and then the old domain controllers have connections to the other 3 original DC's at the other sites. I'd like to just power down the old domain controller one at a time and give it a couple days to make sure there are no issues before demoting them, but I'm curious, will Sites and Services automatically build connections from the new domain controllers just because the old one is offline or will it only do that once I actually demote the old domain controller? If it will do it just by me powering it down, is there a specific time it waits before it can't reach the old DC before it builds the new connections?

Answer 1

The bridgehead selection should happen automatically.
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/ff800799(v=ws.10)?redirectedfrom=MSDN

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Answer 2

As soon as you demote the current one the process (KCC) will nominate a new one.

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Answer 3

Hi

but I'm curious, will Sites and Services automatically build connections from the new domain controllers just because the old one is offline or will it only do that once I actually demote the old domain controller?

The KCC can't detect offline DC, it will continue generate connection objects based on site topology and site links settings.
The KCC stop generate a connection with offline domain controllers when you demote them.

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Answer 4

Hello,

Thank you so much for posting here.

Some information were provided. We could kindly check whether they are helpful.

By default, the KCC runs at 15-minute intervals and designates the replication routes between domain controllers on the basis of the most favorable connections that are available at the time. The KCC creates replication connections between domain controllers in the same site automatically. When there is more than one site, configure links between the sites; the KCC can then create the connections automatically between the sites as well.

Reference: https://learn.microsoft.com/en-us/previous-versions/tn-archive/dd277429(v=technet.10)?redirectedfrom=MSDN

Please let us know if you would like further assistance. Thanks.

Best regards,
Hannah Xiong

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