The WhoIs option will query the WhoIs servers and return the details of registered name or IP address.  If the Show Referrals option is enable, if a referral is returned, then it will query the returned referral server for the information.

This function using the TDL.whois-servers.net server for name lookups, and whois.arin.net for IP address lookups.  It uses the original RFC services on port 43, some proxy implementation may block this port, in which case NetTools will report a 10060 error.