Hello everyone. We have been having some internal debates as to the current Best Practice for internal domain names. I run an IT consulting firm, and we typcially work with small & mid-size businesses, those with 10-200 computers. They are almost always a single Forest and single domain.
Since around the time that Windows 2000 was released, our company standard has been to use theircompanyname.local for the internal domain name for all of the networks for our clients. I believe it was promoted as the Microsoft Best Practice at the time, but to be honest, it was quite a while ago and I really don't recall the details.
I see some suggestions that .local should not be used. In some cases, the reason mentioned is because of some issue with Macs and the Bonjour service (although there seems to be a fix for that.) I also see suggestions to use .lan and .internal.
Lately, I have seen suggestions that the best practice is now to use a subdomain of a registered top level public domain name - such as corp.theircompanyname.com or ad.theircompanyname.com or internal.theircompanyname.com.
And I have also seen suggestions to use a separate/different top level public domain name, such as theircompanyname.net (a real TLD that the company has registered).
Virtually everything that I have seen says that you should ways use different names for the internal network and the external public network (ie. don't use theircompanyname.com for the internal network, and the same theircompanyname.com for their external public network. Although I have talked with one person who insists using the same name is the best way to go.
I am curious to learn what others are doing, and why. I would also love to find a formal document from Microsoft that states their current position on this practice. I searched, but douldnt find anything.
Thanks in advance.