CNAME and MX

Mark.Andrews at nominum.com Mark.Andrews at nominum.com
Wed Apr 12 06:34:48 UTC 2000


> Hi,
> 
> I am fairly new to DNS.  I know the basics, but there are a few things I
> am not sure about.
> 
> First of all, why are you supposed to have only one A record for each IP
> address?  Is that actually stated by the RFC?

	Multiple A records are allowed.  Using CNAMES can reduce the amount
	of work required if a machine is renamed but is not required.

> 
> And say I make a CNAME mail.mydomain pointing to serv100.mydomain can I
> use mail.mydomain as the MX or do I have to use the A record
> serv100.mydomain?

	Any reference to a domain in any record type is supposed to refer
	to the offical name not an alias (CNAME).

	So to answer your question, you cannot use mail.mydomain in the
	MX record.  Also many mail transfer agents (MTA) need the name in
	the MX record to be the name the machine knows itself as. 

	Mark
> 
> Thanks,
> 
> -- 
> Jeremy Lunn
> Melbourne, Australia
> ICQ: 19255837
> 
> 
--
Mark Andrews, Nominum Inc. / Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com



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