I'm not the full bottle on things DNS.

I've got a domain foo.com with web / mail hosting off-site.

I'd like to setup a series of domain entries site1.foo.com, site2.foo.com etc so its easier to SSH / connect to machines located at a variety of site offices.

I've used Dyndns.org to do this in the past but using sub domains of my own domain name would be much easier.

Is this easily implemented on a OS X machine that's already doing other server duties?

Cheers, Antony.