Question: If I just want to know if a domain name is reserved; is it sufficient to use this command and see if any domain name servers turn up, in which case it's reserved?

```
host -t NS example.com

```

It's a lot faster than visiting <http://www.internic.net/whois.html> and typing example.com to get much more detailed results, which I'm not interested in anyway.

Answer: 
Various TLDs have differing requirements for whether name servers are provisioned or not. For example ".de" does require that name servers are up and running and correctly configured before they'll allow the domain registration to proceed.

The technical standards for DNS don't require it though, in fact there's nothing in the core DNS specifications to link together the *registration* of a name with its subsequent *operation* in the DNS.

Therefore, using `whois` is probably the most reliable method, with the caveat that you'll need a whois client that's clever enough to figure out which server to talk to for the domain in question.

That said, checking for the appropriate NS record is a very good shortcut to check that a domain *is* registered, you just can't use the absence of such a record to prove that it *isn't*!
I don't believe that you have to have a DNS pointing to your domain. Even if you had to have a DNS set up, there is no assurance that the box acting as the DNS server isn't down.