My boss won't let us go anywhere with our Active Directory DNS
namespace design until I can get a solid answer one way or another on
the following question.

QUESTION>>>>

Microsoft suggests you use a top level domain for the suffix (.org,
.net, .com, etc.) of your Active Directory namespace. Does anyone know
of a sound implementation reason of why I should/shouldn't use <.ad >
as my forest root domain? I intend to be the only authoritative DNS
servers for that namespace in my network. We have a relatively small
implementation (Single Forest, Single Domain, ~50 Servers) and this
would allow us to start fresh with our internal DNS structure as well
as clearly distinguishing our internal and external DNS. I have read
the following statement From TechNet with regards to this situation
"Windows 2003 deployment kit, designing a DNS namespace."

The disadvantage is that this configuration requires you to manage two
separate namespaces. Also, using a stand-alone internal domain that is
unrelated to your external domain might create confusion for users
because the namespaces do not reflect a relationship between resources
within and outside of your network. In addition, you might have to
register two DNS names with an Internet name authority if you want to
make the internal domain publicly accessible.)

Are there any other relevant reasons than the above argument provided
by Microsoft? Are there any sound business or implementation reasons?
Are there any relevant reasons why this may be a superior solution to
using a top level domain suffix?

Also read>>>>

I have read in the "Best Practice Active Directory Design for Managing
Windows Networks (2000)" which states

"Note As a best practice use DNS names registered with an Internet
authority in the Active Directory namespace. Only registered names are
guaranteed to be globally unique. If another organization later
registers the same DNS domain name, or if your organization merges
with, acquires, or is acquired by other company that uses the same DNS
names then the two infrastructures can never interact with one
another.
Add a prefix that is not currently in use to the registered DNS name
to create a new subordinate name. For example, if your DNS root name
were contoso.com then you should create an Active Directory forest
root domain name such as concorp.contoso.com, where the namespace
concorp.contoso.com is not already in use on the network. This new
branch of the namespace will be dedicated to Active Directory and
Windows 2000 and can easily be integrated with the existing DNS
implementation. The rules for selecting a prefix are listed in Table
9.
Table 9 Rules for Creating a Prefix for an Active Directory Name
• Prefix rule     • Explanation