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I have 2 domains. Either of them have 2 domain controllers. So my architecture is: Domain 1. - DC1, DC2 and SQL Server. Doman 2. - DC3, DC4 and IIS Server so which one these computers I must back up for active directory?

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migrated from Feb 11 '12 at 5:16

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Just to be clear, with what you have described there is no single computer that contains the information for both domains, so you will need to back up at least 2 machines, one for each domain. – John Gardeniers Feb 11 '12 at 11:12

One or more of your domain controllers have a copy of the Global Catalog. Figure out which one(s) have a copy of the GC - one of those should be what you back up.

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You only need to do a System State backup of one DC in each domain to be covered, but, given you've got four DCs total, I'd be safe and just back all four up.

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You dont really need to backup the other DC's which are there for other roles like file server, print servers. Just blindly backing up all the DC's is completely illogical & results just in Redundant data. – Dave Feb 10 '12 at 19:08

I would always back up the system state of every domain controller. It doesn't take much storage space (or effort), so why would you consider not doing this? It's a no-brainer to me, and simply not worth the risk for the minimal effort involved.

What if you had replication issues? These aren't always immediately obvious, and could go unnoticed depending upon how proactive the admin is with log checking.

Ask yourself, Are you sure you can recover from a backup of the domain from a single DC? Are you prepared to take that risk, or is it worth spending 30 mins setting up a scheduled job to back up the other DCs?

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Every Domain has a Primary Domain Controller Which is responsible for the Active Directory. Here you have two DC's one of which acts like Additional Domain Controller which is can be responsible for other Domain-wide roles like file server, print server etc. So try to figure out which one among the DC1 & DC2 is your PDC & backup it. same goes for Domain2. Hope this helps.

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This is really not accurate. Every domain has a PDC /Emulator/ which performs some additional functions. There's nothing (from a data perspective) that's different about the PDCe versus other DCs. – Brian Desmond Feb 10 '12 at 17:00
I know but they host the other services on the other DC's so that they can have a dedicated DC for active directory – Dave Feb 10 '12 at 19:06
Your knowledge about this seems to be outdated by about 15 years – MDMarra Feb 11 '12 at 14:05

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