On: Just type `whois Microsoft.com` in your shell

[jalada]

Interesting. Can someone explain what is happening here?

[janjongboom → jalada]

I believe that whois does a wildcard search for all domains known to start with microsoft.com, and some funny people registered subdomains under their own domains that start with microsoft.com. But maybe I'm wrong :-)

[mappu → janjongboom]

OK. Next question - why does the verisign whois server know about arbitarily nested subdomains, instead of only top-level registrations?

[mattzito → mappu]

Take a look at my response upthread - basically, they're not sub domains, they're arbitrarily registered name server entries to provide glue to other lookups. The Whois record is just the side effect

[AdamGibbins → janjongboom]

Correct, you can do an exact match using whois 'domain microsoft.com'

[jalada → janjongboom]

Ah yes, same applies to facebook.com and many others.

[pprevert → jalada]

These are glue records. If a nameserver is under the domain name he is authoritative for, it has to be declared to the registry with its IP address as to avoid circular dependency, ie:

* Q: What is the nameserver for bleh.blih ? * A: ns.bleh.blih * Q: Thank you fine sir. What is the ip for ns.bleh.blih ? * A: Ask nameserver of bleh.blih. * Q: But I just...

And so on. Such declared hostname/ip nameservers are called glue records.

Whois databases search glue records too (and only return a limited number), and this is what you see here.