easy squeezy...
For my personal system, I am using one of the free DNS services that can be found on the internet. My ISP was TOTALLY "DNS Clueless" and wouldn't do it for me (even though they say it's ok to have a web/ftp/mail server running on the connection). Interesting thing is... the free DNS service says "here... write your own zone record and we'll add it to the server" so I had to dig a little (well... a LOT) to figure out how to do so.
As far as I know, and believe me I'm NOT the expert, when your DNS service (whoever they may be) made the zone record for the domain sinfield.com they will also have created a couple of aliases. Like:
www.sinfield.com and maybe ftp.sinfield.com. Also, If you are wanting your email service to work, they will have to have created something called an MX record (probably pointing to mail.sinfield.com).
That is really the extent of my knowlege at this time. If anyone knows of a place to get REAL strait answers please let me know, I don't mind RTFMing if know where to go to get the FM. IYKWIM. (oops... if you know what i mean that is).
Once again... before you annoying little... well... anyway... before someone wastes their time telling me that linuxdoc has a DNS howto, I've read it... and glad I am too! I would have NEVER figured out how to install BIND without it, But last i looked, It didn't have any further pertinant info than that about the topic on hand.