Where is the WHOIS?

When you change the Whois information, or the DNSs of a domain, it takes ~24 hours so it is updated through the world, BUT when you register a new domain name, in the same second it becomes Unavailable at all registrar websites.

Where does the registrar website go to check whether a domain is available or not?

Where is th MAIN WHOIS DATABASE?

Borg's right. It just means the names will be available for distribution faster - not that they will be distributed faster. You might see up to 12 hour faster propagation of .com, .net, etc., but there are other factors involved.

DNS servers are supposedly governed by the TTL (Time To Live) setting for your domain which states the number of seconds to elapse before checking the domain source for updates to it. It's a suggestion, not a rule. The reality is that most DNS servers check once every 12-48 hours.

About a week before I move a domain however, I change the TTL to something like 5 minutes so when I do move it, it will be picked up faster by those servers who do honor TTL. The trick is to set it back 2 whatever your host recommends (12-48 hours usually) after the move. Many hosts either don't allow TTL changes or keep an eye on them as very low TTL is a symptom of a spammer. Not to mention the bandwidth wasted for the next 10 years once you've actually moved the domain.

The way DNS propagates is that DNS servers "close" (in Network topology) to the source DNS Servers get it first. Servers a little further out may check them and servers even farther out may check the second tier servers. Depending upon how frequently each server checks, it could take a week to propagate world wide.

One of the advantages to picking a host on ot close to Internet backbone facilities is not only speed of access, but also speed og DNS propagation.

I usually tell my clients to wait 1-3 days for US propagation, and 5-7 for world wide. .org and .country domains are on the slower side of those parameters. .info domains can be either fast or slow.