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tomdlgns
Premium
join:2003-03-21
Chicago, IL
kudos:1
reply to Steve

Re: DNS - A, MX and PTR records - Silly quesiton

said by Steve:

said by tomdlgns:

The idea is that the servers listed as secondary MX servers have some out-of-band way of knowing when the primary servers are back online.

ETRN is an in-band way of knowing this.

sorry, you lost me.


Steve
I know your IP address
Consultant
join:2001-03-10
Yorba Linda, CA
kudos:5

said by tomdlgns:

sorry, you lost me.

When the final mailserver is back up, it can phone home to the backup (via port 25/tcp) and use the ETRN command that essentially says "This would be a great time to scan your outgoing queue", at which time it presumably finds that it can consummate the final delivery.

No out-of-band mechanism required.

Steve
--
Stephen J. Friedl | Unix Wizard | Security Consultant | Orange County, California USA | my web site

tomdlgns
Premium
join:2003-03-21
Chicago, IL
kudos:1

ok, but were you correcting something i posted or adding more information?

i just copy/pasted from the website and included a link.