Got a question about DNS, I'd be much appreciative if anyone could lend
some insight.

I have an internal office network running MS Small Business Server as a
PDC/Exchange server.  SBS apparently insists on managing DNS in it's
domain.  Internally I also have some web servers that are used for
development.  Everything in the office sits behind a Linux
gateway/firewall.

Externally I have a real, er, Linux DNS server running BIND.

The setup I inherited has a subdomains pointing into my dev web server for
external access to current projects.  This is something my people want, so
they get it.  Issue with the current config is that there are two
subdomains created for accessing the same content.  My people were told
that they needed to access this content with an
http://internal.mydomain.com from within the office and
http://external.mydomain.com from outside the network.  There is constant
complaining about the inconvenience associated with this config.  Although
the complaining may be petty it's what I get paid to deal with apparently.

DNS is configured for http://internal.mydomain.com to resolve to the
private IP address of the development server and
http://external.mydomain.com resolving to the public IP address that port
forwards to the same server.

I'm far from a DNS guru, in fact this job is the first that I've ever had
to deal with anything more than understanding the general concept to DNS. 
Is there any reason why I could not set up DNS on my SBS for
http://dev.mydomain.com to resolve to a private ip of, say, 10.0.0.111 and
set the same subdomain on my external DNS server with a public ip of my
gateway?

I have made some tests and all seems to work well as long as I have
primary DNS on my machine set to my SBS server and secondary to the ip of
the office gateway which has my external DNS as the first entry in
/etc/resolv.conf?

The previous admin seems to think this can not be done and I fail to see
the issue.

Thanks!

--
timo