looking up the NS record for a domain is the best place to start. The root DNS zone files are updated with the same frequency as the WHOIS databases, in most cases, and DNS is a much higher performance protocol than WHOIS. If you find a domain is available through DNS, you should then check WHOIS as a backup, because domains can be placed on hold, which means the NS records are withheld from the root zone files. Note that WHOIS isn't wholly accurate, either -- Verisign frequently shows domains as having expired when the domain is not available at the registry.
Rob's right that you can run a WHOIS lookup with a fairly simple Tcl proc. The main thing to watch out for is that some WHOIS servers have multiple IP addresses, and the AOLserver calls to connect a socket will only use the first address returned. You can fairly easily code a module that uses resolver queries to do lookups of the DNS NS records. (I've done a lot of this before.) > > Looking up a host in DNS doesn't determine whether the domain is > > available. For that you need to do a whois lookup. Fortunately that's > > TCP-based, so you can do it entirely with Tcl in AOLserver.
