If I name my Active Directory domain "foo.local", what domain do I tell the (Windows) computer to join to? Do I put in "foo.local" or just "foo"?


You can join the domain using foo or foo.local. Foo is the single label NetBIOS name of the domain and foo.local is the DNS FQDN of the domain. Using either one to join the domain is valid, although I prefer to always type the FQDN.


You would put foo.local, but you shouldn't use a .local TLD for an AD domain.

  • Mark: I have worked for a company that had named its AD domain 'company-initials.local', with a NetBIOS-friendly name of 'companyname'. Although I was not involved in the naming decision, which took place before my arrival, I observed no obvious ill effects. Given your extensive knowledge of the subject, I am very curious to understand why you would recommend against this practice. – Skyhawk Jun 25 '10 at 23:12
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    @Miles Erickson - .local isn't a real TLD. What's to say it won't ever become one? If all of a sudden someone else owns yourcompany.local, you have the "internal DNS thinks it is authoritative for a zone that it really isn't" problem. The generally accepted way of doing it safely is to make it a subdomain of a current domain that you own that isn't routable on the Internet. Something like ad.yourcompany.com or internal.yourcompany.com, etc. – MDMarra Jun 25 '10 at 23:15
  • @Miles Erickson, I suspect you never had computers running OS X on that network either. Bonjuer does weird things where .local is used. Read up on the discussion on some of the questions I linked to. – Zoredache Jun 26 '10 at 3:50
  • & @Zoredache: Thanks, makes perfect sense. I appreciate you taking the time to explain! – Skyhawk Jun 27 '10 at 5:25

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