Promoting new DC in a remote site

There are two sites - both are in the same domain.
There are two domain controllers in site A - only one in site B.
The one DC in Site B has a corrupt AD database and is no longer syncing with Site A.

I will replace it with a new DC and plan to demote the old DC and then promote the new one.
I am worried about what could happen if there are any problems promoting the new DC.
With the old DC demoted at that point, would users in B still be able to log in using the DC's at Site A?
Is there something I can check first to confirm if user logins will work even with no DC on that site?
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Tom CieslikIT EngineerCommented:
How those sites are connected ? via VPN ?
Is there DHCP server on side B domain controller ?
SeeDkAuthor Commented:
Yes VPN and yes it has DHCP.
Radhakrishnan RSenior Technical LeadCommented:

"With the old DC demoted at that point, would users in B still be able to log in using the DC's at Site A?" - Since it's a single domain, the users will be able to login to the domain (but will be bit slow due to 'site to site' or 'VPN'). What's the DNS current set for the Site B domain users? I hope you have pointed 1 DC's DNS from site A and 1 from site B? if so, no impact. What about DHCP? is the site B machines getting the leased IP's locally? if so, there is a problem getting IP's on site B. If the DHCP located on site A then no issues.

Demote the old DC, metadata cleanup, then promote the new DC.

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Lee W, MVPTechnology and Business Process AdvisorCommented:
Something to check first?  This probably should have been done in the beginning and at regular intervals to validate everything was working fine (along with a DCDIAG) - turn off the remote DC.  Ask people to login and connect to network resources.  If it doesn't work, you'll know there are other problems. (Though cached logins may allow it to work anyway)
SeeDkAuthor Commented:
@Radhakrishnan R

DNS - The PCs have a backup DNS entry to Site A
DHCP - PCs are getting the IP's locally. Would assigning it statically (only temporary) to the PCs help workaround this problem?
Shaun VermaakTechnical Specialist IVCommented:
SeeDkAuthor Commented:
Another question, if i promote the new one first before demoting the old one.
Is there any risk that the corrupt database on the old one will be copied to the new one?
Shaun VermaakTechnical Specialist IVCommented:
If you are concerned about that, specify a source server from the advance options during promotion
SeeDkAuthor Commented:
Thank you everyone - went smoothly.
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