Window Server 2012 R2 Setup and backup Server

Kinderly Wade
Kinderly Wade used Ask the Experts™
Dear Experts,

I have a question regarding to the Window 2012 R2 server DNS, AD, and DHCP setup. Say I have a server setup with the these services DNS, AD, and DCHP. If I wish to configure a failover or a copy of this server, what will be a good way to setup? If I do need to setup another server will I need to keep it up all the time so in case the main server fails the backup can take over? How will I know if the user are on the main or the backup? Will the backup server cause conflict with the main server? Thanks. (sorry that I have so many question in one)
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It is always a good idea to have two servers running both DNS and AD. Replication between the two takes care of issues of when is down, the other picks up. They would be domain controllers and global catalog servers. If you make a change to one, it replicates to the other and vice versa.

Previously they used to be known as PDC and BDC (Primary Domain Controller and Backup Domain Controller) back in the days of NT, but that went away when Win2000 was introduced.

Regarding DHCP, because I'm not too familiar with setting up a split-DNS, I chose just to have my DHCP server a separate box altogether. I'm pretty sure the concept of split-DNS is simple (I believe set up the scope so that one server handles half and the other server handles half), but if I had any DHCP issues, it doesn't affect my DCs.

Worse case scenario would be to assign static IP's to my clients and they work along until I figure out what's wrong with the DHCP server. But that's just me.
Also, in a real emergency (main server got toasted), you can seize the FSMO roles.
Principal Support Engineer
Regarding AD and DNS, you can simply promote a second domain controller in the domain and make sure your DNS zones are AD-integrated. As long as they are, the DNS data will be replicated between the DCs along with the rest of the AD data (assuming replication is is good working order, of course).

DHCP is a bit different, because its database can't be integrated with AD like a DNS database can. However, beginning in Windows Server 2012, Windows allows you to configure DHCP Failover, which provides true redundancy for DHCP without requiring a full failover cluster configuration or a split scope. Information on DHCP Failover, as well as instructions for setting it up, can be found here.
Kinderly Wadeprogrammer


Hi Experts,

THanks for the prompt reply. Is it ok for me to have more than one backup and can I demote my main as backup and convert one of the backup as my main? thanks. I am taking down one of the DC from the server because that server is too old. If I have a backup DC then I can simply convert the backup as main (assuming I have the failover and replication of the DHCP, AD, and DNS info on the backup server).
DrDave242Principal Support Engineer

Yes. As far as AD goes, there's no such thing as a primary and backup domain controller anymore, as efrimpol said. If you're going to demote a DC, just make sure that replication has been working first. You don't even have to transfer the FSMO roles to another DC ahead of time, as this will be done during the demotion, although transferring them yourself is required if you want control over where those roles end up.

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