Question about MX records
John
vo at eudoramail.com
Tue Mar 9 11:51:32 UTC 2004
Barry Margolin <barmar at alum.mit.edu> wrote in message news:<c2io9c$1mm0$1 at sf1.isc.org>...
> In article <c2idv8$otu$1 at sf1.isc.org>, vo at eudoramail.com (John) wrote:
>
> > Hi all:
> >
> > I have two mail servers:
> >
> > IN MX 10 server1 preferred.
> > IN MX 20 server2 second choice.
> >
> > My questions are:
> >
> > 1. What is considered failure? if server1 has a problem
> > and gives the incoming connection "connection refused"
> > message? will the sending mail server jump to server2
> > then? how does the dynamic work?
>
> Yes, a failed connection attempt -- either a timeout while trying to
> connect or a connection refused -- is the only thing that will cause
> most mailservers to fail over to a backup MX. I think RFC 2821
> recommends also failing over due to certain types of errors encountered
> after connecting successfully, but I don't know if many mailers have
> been updated to conform to this.
>
> > 2. If the DNS server that the incoming mailserver uses
> > had cached the info including the old server1 info,
> > will the mail server then keep trying it even though
> > it's down?
>
> It will keep trying them in order -- first server1, then server2.
>
> BTW, do you have a question about the BIND nameserver? It seems like
> your questions are about mailservers, and would be more appropriate in a
> mail-related newsgroup.
This is a question about MX records and how they work.
Thanks for the answer.
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