Hey all,

A couple of days ago, my server was complaining with  "CNAME lookup failed
temporarily" when delivering emails to domain "repsol.com".

At first i couldn't  understand what the problem was. Querying MX records
for that domain returned valid results.

I turned to the dns caching server, and noticed that qmail is making a "IN
ANY" query before actually doing a "IN MX".

For instance, when delivering an email to google:

  Mar 31 01:03:24 mail named[24968]: client 127.0.0.1#53542: query:
gmail.com IN ANY + (127.0.0.1)
Mar 31 01:03:24 mail named[24968]: client 127.0.0.1#57416: query: gmail.com
IN MX + (127.0.0.1)

I noticed that the same query for "repsol.com" resulted in failure.

$dig @8.8.8.8 in any  repsol.com

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.8 <<>> @8.8.8.8 in any
repsol.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 27672
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;repsol.com. IN ANY

;; Query time: 2036 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Wed Mar 31 01:13:42 2021
;; MSG SIZE  rcvd: 28



I wonder why qmail is issuing a "IN ANY" query.

Also, I'm finding some info on the internet referring to the idea of
deprecating the support to "in any" queries, like this one:
https://blog.cloudflare.com/deprecating-dns-any-meta-query-type/


So, any thoughts about this? Am i wrong about qmail doing "IN ANY" queries
before "IN MX" queries? Im afraid this may this pose a problem in the
(near) future in case everybody starts deprecating the "IN ANY" queries.

cheers,

J

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