I haven’t seen a IP address in a MX record in the last 5 years. In the 16 years since that was written, the email world has changed a lot. Email systems are larger, and tend to run by email professionals who know the standards. This did not happen:
It's reasonably clear what will happen to this protocol in the future. System administrators will continue to use dotted-decimal domain names. There will be occasional failures from other MTAs running under other DNS caches; the MTA implementors and the DNS implementors will react by adding support. Eventually, no matter what DNSEXT does, dotted-decimal domain names will be a de facto standard. And the DNSEXT working group never changed the MX standard. Sometimes it might better to go with the Standard way of doing things. You can’t keep adding non-standard cruft to your services, and expect a smooth lifecycle. Tom > On Sep 13, 2017, at 2:03 PM, Joe Williams <[email protected]> wrote: > > Thanks to asking around on twitter I think we have the why, > https://cr.yp.to/djbdns/namedroppers/20000220195445-21265-qmail@cr-yp-to > <https://cr.yp.to/djbdns/namedroppers/20000220195445-21265-qmail@cr-yp-to> > > https://twitter.com/jedisct1/status/908072827890405376 > <https://twitter.com/jedisct1/status/908072827890405376> > > On Wed, Sep 13, 2017 at 1:52 PM, Joe Williams <[email protected] > <mailto:[email protected]>> wrote: > Thanks for finding that Tom! > > On Wed, Sep 13, 2017 at 1:49 PM, Tom Samplonius <[email protected] > <mailto:[email protected]>> wrote: > dnscache is a pretty weird. From the webpage at > http://cr.yp.to/djbdns/dnscache.html <http://cr.yp.to/djbdns/dnscache.html> > ... > > > “dnscache handles dotted-decimal domain names internally, giving (e.g.) the > domain name 192.48.96.2 an A record of 192.48.96.2." > > > So it looks like dnscache will return a the IP address back for any A queries > for a IP address. And it looks like it returns a basically infinite ttl. > > Why do you need this behaviour? I used to use dnscache many years ago, but > dropped it when powerdns-recursor became available. I never noticed this > “feature”, and never had anything break when it went away. > > > > >> On Sep 13, 2017, at 1:17 PM, Joe Williams <[email protected] >> <mailto:[email protected]>> wrote: >> >> Thanks for the reply Tom, I wish I knew why as well. Right now I am just >> trying to make my unbound config backwards compatible to not break code that >> expects an answer for an IP address. >> >> On Wed, Sep 13, 2017 at 1:05 PM, Tom Samplonius <[email protected] >> <mailto:[email protected]>> wrote: >> >> > ;; ANSWER SECTION: >> > 10.36.129.10. 655360 IN A 10.36.129.10 >> >> >> Looking at this answer, I’m not sure why anyone would want this behaviour? >> >> Is dnscache trying to dampen RFC1918 A queries by doing this? >> >> >> Tom >> > > >
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