Round Robin Mail Exchangers

[Barry Margolin]

In article <cbv4if$2901$1 at sf1.isc.org>,
 Mike Diggins <diggins at McMaster.CA> wrote:

> Would it be advisable to create an A record that resolves to multiple IP
> addresses such as :
> 
> mailer		10	IN	192.168.1.1
> mailer		10	IN	192.168.1.2
> mailer		10	IN	192.168.1.3
> 
> ...then add 'mailer' as an MX record for several hosts that wish to
> receive mail? This solution would allow me to make changes to the mail
> exchangers quickly, and in one location, without editing the records of
> each host it was added to. The alternative is to add each of the three
> mail exchangers to each host individually. I have about a hundred that
> need to be changed, and may need changing again in the future.

Yes, this is a reasonable approach.

> Another related question, if the sender resolves the mail exchanger to
> 192.168.1.1, and it happens to be down, would it try again or would that be
> it? It occurs to me that listing each of the mail exchangers individually
> would result in each one being tried separately until it succeeds. Or have
> I missed something!?

Yes, it's supposed to try multiple addresses.  See RFC 2821 for details 
of how SMTP servers are supposed to operate -- your questions aren't 
really BIND-specific.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***