Paid subscribers now benefit from increased domain testing speed and a root server trace of how a domain resolves.

The rootserver trace not only provides another means of checking a domain resolves correctly, but can also pick up a subdomain that is being resolved directly by the TLD (top level domain) servers. A subdomain that is serving as a namerserver may have its address registered via the registrar as a nameserver. In which case that address may be resolved at the TLD level. This will of course cause problems if you have altered the address at the domains nameserver but not at the registrar.

The domain testing now also benefits from some more subtle interpetations, for example MX records may not be expected at the subdomain level.