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: 
NS records are not necessarily required for registered domains. The whois service is your most reliable option.

Note that most Unix systems and Mac OS X have a "whois" command line program that is really quick to use:

```
whois stackoverflow.com

```
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.