Reasons to NOT use .local or .pvt top-level domains for AD

Q. Can I use the .local or .pvt top-level domain (TLD) names as part of an Active Directory (AD) tree name? -RSS

Uh, because they are not reserved?

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.