Best Practice for internal domain names

Posted on 2013-01-02
Last Modified: 2015-06-23
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 or or

And I have also seen suggestions to use a separate/different top level public domain name, such as (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 for the internal network, and the same 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.

Question by:wolfconsultinginc
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Mike Kline earned 25 total points
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Are you planning to use office 365 or dir sync at some point, if so good blog from Mark

Our internal domain name is different and many are still different.  We don't plan to change because a domain rename is a pain.  


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by:Alan Hardisty
Alan Hardisty earned 25 total points
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Please have a Read of GoDaddy's statement regarding Internal Domain Names:

The .local is going to be dead in the water and as to what standard best practise is going to be, that is anyone's guess.

Either or should be fine, all that needs to be working is DNS and if you use the same name internally as externally, then you need to replicate DNS settings in internal DNS and External DNS.
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by:Bill Bach
Bill Bach earned 25 total points
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I can give you our own reasoning:

I never really liked the ".local" naming convention.  I think this was done for companies that lacked Internet access.  I might consider this for a company today if all computers were really off-'Net, but I haven't run into a company like this in some time.

Using the "real" domain isn't a good idea either.  For one, if they have an internally-hosted server (like www) that is visible from the outside, as well as inside, then the name resolution can get sticky.  You have to have an internal DNS server for providing internal addresses, and an external DNS server for providing internal addresses.  Now, you're maintaining two sets of DNS entries -- Ugh!  It asks for trouble.

Our solution has been to use subdomains. This is easy to do, and you can easily set up a permanent DNS server at a DNS provider for all global addresses from the outside world.  Then, you can create an internal subdomain of DNS on the internal server (that nobody else knows about) for all local computers and local addresses inside the firewall. It's hard to say if this increases security (though if the DNS subdomain is inaccessible from the outside, it definitely helps hide computer names) or not, but it does appear to make it easier to use.  Then, a user who wants to hit an internal server from inside the network knows that he can hit, and if he wants to hit the public side (outside the firewall), he can use

The downside to this is that users may need to be a bit more savvy -- remembering to add the "local." in front of the name, but it does make it very clear which resource you are accessing, then.
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irweazelwallis earned 25 total points
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MS recommend domain.local i.e. you company is northwind traders and you have external registered name of you would use northwind.local

if you have a separate internal and even better a generic internal name i,e, company.local then you don't have to deal with things like split DNS which causes issues with Exchange, wbe sites etc.
It also means that data leakage from your domain is generic and not very useful to people trying to hack
It also means if you get bought or you buy you don't get issues like needed to change the domain name to either get rid of a company name because you can't legally use it any more or incorporate assets from another company easily
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by:Seth Simmons
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This question has been classified as abandoned and is closed as part of the Cleanup Program. See the recommendation for more details.

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