Checking domain name availability with DNS records

Question

How accurately can a domain name\'s availibility be determined by checking for the existence of NS or SOA (Start of Authority)

Answer 1

I've also been using the dig method to test for the existence of a domain before registering but about 10% of the time, it returns domains that are NOT available as available. This is because the owner of the domain hasn't set up any records for the domain. So what I've decided to do is:

1. First check via dig method.
2. If domain appears to be available, then check using whois.shtml

People will go through a bunch of domains that are not available and this doesn't waste the allocated requests that UniForum provides. Only if something appears to be available do you check on co.za itself. It seems to me to be the only reliable way to do this WITHOUT losing access to co.za/whois.shtml due to sending them a million requests :)

Answer 2

Tried whois and it gives me weird results (google.fr as free!) so I tried a Windows command: nslookup yourdomain and you will get its IP if it is registred.