Dns question

[Sina Bahram]

Hi all,

I hope everyone is doing well.

I appologise for the off topic message, but I know that a great deal of you
are enthusiasts in networking, and are quite more well versed than myself in
DNS, which is where my question arises.

I am building a utility that checks to see if a particular domain is
registered or not.

Think of it like a stripped down personalize version of whois, if you will.

My problem is that I have yet to figure out the absolute minimum
requirement, in terms of something that can be programmatically determined,
that says: hey this .com is taken.

I am using the net::dns module from CPAN in my perl script, and I have tried
looking at the SOA record, because that is what I have picked up from my
documentation and google runs as being the absolute requirement.

Yet, I still get websites like

www.hospital.com

And

www.patient.com

Which do not return SOA records to my program, yet they are owned ... I
think both of those, since 1997.

So, my question is, what is the absolute minimum? I would even appreciate
documentation pointers, but I just can not learn DNS in and out right now,
due to other job, research, and student requirements; however, I'm more than
willing to RTFM, as it were, I just haven't found anything that doesn't
point me to either MX or SOA records.

Thanks so much for any assistance.

Take care,
Sina