MX record and PTR questions

[wally]

Hi there, something always bugged me with MX records.

In most domain setup examples we see an mx record setup such as
(and forgive the exact syntax - this is just an example)

domain.com.au  MX 10  mail.domain.com.au
mail A 202.123.456.789

My question is - does the name "mail" have any significance at all or
is just an alias that is resolved by the A record. If  my server was
called server1 (or fred or whatever) could I still set it up as:

domain.com.au  MX 10  mail.domain.com.au
mail A 202.123.456.789
server1 A 202.123.456.789 ; is this record even needed????

or would it be best to set it up as

domain.com.au  MX 10  server1.domain.com.au
server1 A 202.123.456.789

Also if my server was called server1 - would the reverse PTR have to
read server1.domain.com.au or the name specified in the MX record (in
the first case mail.domaim.com.au)

Hope someone can set me straight.

Cheers
Wally