Question : dig command output

I am wondering where to find documentation on the unix dig command.

I have done some looking, and even the man page does not explain what the output means. Points for either a document that explains the output, or in particular the line in the ANSWER section. Especially the number that comes after the domain. As in the following:

www.rephunter.net.      403      IN      A      216.17.40.100

What is the 403?

Answer : dig command output

That's the TTL (time to live). If you query the hostname a little later, the number will be smaller. At 0, the domain will be refreshed.