DNS recs, a beginners question

Dear all

I know this is a really newbie question. But I have to help
a public school to solve some problems in their webserver/formmail,
and have no way of testing since the DNS is done at a beaurocratic
place. I can tell them _once_ how the DNS should look like, and
there's no reverse :(

This is the setup:
- The school has its own domain, say schoolx.yz.

- They run this web-server with the public IP-address a.b.c.d.

- We have the need to run a SMTP daemon on the same server

I would like to

- keep the canonical name of the machine neutral, say
iron.schoolx.yz. i.e the reverse lookup of IP a.b.c.d
should give iron.schoolx.yz

- www.schoolx.yz should be an alias to iron.schoolx.yz

- mail.schoolx.yz too

- iron does _not_ relay mail

- only the host should be able to send mail, calling
to the SMTP daemon of the localhost.

- the outgoing mail should carry from addresses in the
form user@schoolx.yz

- local users and mail aliases should recieve mail addressed
to user@schoolx.yz.

- our provider's mail server should store incoming mail
in case the machine or the SMTP daemon is down

So it is a straightforward setup with no tricks.


Could a friendly soul post a configuration for bind
including the reverse lookup?

As already mentioned, we have to submit that to this
governmnet place, there's no way of "talking" to them :(


regards
Arun