Creating a backup domain controller

ahmad1467
ahmad1467 used Ask the Experts™
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I am looking for document that explains the best way of adding a backup domain controller to our existing network. I presently have a Windows 2003 VM server that is running AD, DNS, and DHCP.  I want to create another server that will take over if the primary goes down.  So far I have created a new Windows 2003 VM server and just added it to the domain. My reason for doing this is so that if my main domain controller goes down I have another one to fall back to. Is this a good idea to do?  

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Top Expert 2013

Commented:
It is a great idea!!

So since you want just another 2003 box then no schema updates necessary.

It is already a member server you can run dcpromo.  Select "additional domain controller for an existing domain.  When that is done and your computer reboots you can install DNS on the box and also make it a global catalog server.

Let replication happen and now you have a backup AD/DNS/GC

check event logs, verify replication using repadmin, check the health using dcdiag.

Point clients (static and DHCP) to this box for secondary DNS.  

Also add its own IP as a second DNS address in the NIC properties of the new DC

Thanks
Mike
Lee W, MVPTechnology and Business Process Advisor
Most Valuable Expert 2013

Commented:
No such thing as a backup - all DCs in an Active Directory environment perform authentication and are fully writeable.  HOWEVER, there are 5 FSMO roles typically held by the first DC (and which can only be on ONE DC at a time) - any or all of which COULD be down and not immediately impact your environment.

Basically, assuming you are using the same version of Windows Server, make sure the new server is on the domain and run DCPROMO and make it a domain controller in an existing domain.  That should do it.  (It should also run DNS for you and be listed as a DNS server in your workstations network settings).  

BEFORE doing this though, I would create a backup of the existing VM JUST IN CASE something goes wrong.

Author

Commented:
Ok thank you, I will give this a try tonight. Would I run dcpromo on the new server or the existing domain controller?  
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Lee W, MVPTechnology and Business Process Advisor
Most Valuable Expert 2013

Commented:
The new server - you run it on the old server, you could demote it and remove Active Directory.
Senior Solutions Architect
Commented:
You use DCPROMO to promote and demote Domain Controllers.
So run it on the new server to install AD and run it on the old server if you want to remove AD.

Author

Commented:
I am in the process of going trough the Active Directory Installation Wizard and It’s recommending that I store the Database on a separate hard disk but I only have a C: drive on this server do you see that being a problem.

Thanks

Author

Commented:
I have just added the DNS snap in to my second domain controller then restart the server when the server came back up it automatically replicated the DNS from my first domain controller. Is that all I needed to do to add a secondary DNS server?

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