A. Companies often use a .local or .pvt TLD to name an AD tree. However, as I explain shortly, it's better to use a standard naming method--for example, create a name by using a subdomain of your company's DNS address space (e.g., if your company's DNS domain is ntfaq.com, you could name your AD tree ads.ntfaq.com). When you use this method, though, you must remember that the DNS information for the AD tree is hosted on internal DNS servers, not on your external DNS servers. This means that external users can't see information about your internal infrastructure because external users can access only the external DNS server, which has no information about your internal infrastructure. Alternatively, if you want to create a second-level name for your AD domain, reserve another name--for example, ntfaq.net--but don't set your AD domain to the same name as your external name, to avoid causing confusion in name resolution.

If you're determined to use a nonstandard TLD in your domain name, avoid the use of .local or .pvt because they aren't reserved. Instead, use one of these reserved top-level domains:

  • .test
  • .example
  • .invalid
  • .localhost

You can find more information about these names in Internet Engineering Task Force (IETF) Request for Comments (RFC) 2606. Remember, if you use these nonstandard DNS names, you can't obtain certificates from a third-party Certificate Authority (CA), which might cause problems for your organization.