Unable to add a second forest in AAD Connect

Question

Hey Everyone I have customer who is trying to add an addition forest to his AD Connect. They do not have a trust set up between the 2 forest and they will not establish one. When setting up ad connect we are getting the following error " The domain specified in the credentials does not exist or cannot be contacted" Any ideas what could be causing the problem?

Thanks for the help

Answer 1

Hi @stavros mitchell ,

it's possible to ping the untrusted AD domain (and domain controllers) by name from the server running AD Connect?

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten

Answer 2

Hi @stavros mitchell ,

all required ports are "allowing communication" between AD Connect and the DC of the untrusted AD?

https://learn.microsoft.com/en-us/azure/active-directory/hybrid/reference-connect-ports#table-1---azure-ad-connect-and-on-premises-ad

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten

Answer 3

Hi @stavros mitchell ,

I don't know if your DNS server, used by the AD Connect VM, got the forward lookup zone of the untrusted domain or if you are using conditional DNS forwarding.

But this would be my check.

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten