I’ve been implementing Configuration Manager in an organisation recently which has multiple domains including a single label domain. Now to cut the whole post short I’m not going to step you through how to implement in a single label domain, it can’t/shouldn’t/isn’t supported to be done unless you set up a disjointed DNS namespace. I’m installing Configuration in a sub domain and that is all happy and wonderful so far. One thing caught my eye in the console though and I just wanted to write it down and put it out there for the folk who may come across this one day. Here’s the setup with some fictional representative names…

• ConfigMgr Current Branch – Single Primary site.
• Single label domain = donkey
• Sub domain = eeyore.donkey
• Forest = donkey

So according to Microsoft we can’t use the “donkey” domain as it is now:

The single label domain in Active Directory Domain Services must be configured with a disjoint DNS namespace that has a valid top level domain.

For example: The single label domain of Contoso is configured to have a disjoint namespace in DNS of contoso.com. Therefore, when you specify the DNS suffix in Configuration Manager for a computer in the Contoso domain, you specify Contoso.com and not Contoso.

https://technet.microsoft.com/en-us/library/mt617258.aspx

I guess according to this we could use the “donkey” domain if I set up the disjointed domain name in DNS for something like “donkey.kong”. But we’re not doing that as we have another option so we’re using “eeyore.donkey” for our installation domain. All clear? 

When you install in the “eeyore.donkey” domain all will/should install fine (it did for me). However when you come to add a site system role to your primary site server you may notice that the console spits out an exclamation at your forest – donkey.

Basically all you need to do is amend the Active Directory forest to eeyore.donkey and you will be fine to continue. Certainly in my tests this hasn’t proved to cause any issues and I’m guessing it’s a basic validation function in the console form that looks for a word.word format.

That’s it! Let me know if anyone else has or does come across this one.

/Peter