Sendmail or DNS? I can't tell.

[Kirk Strauser]

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I'm trying to send email to a friend at an ISP called mo-net.com .  Whenever
I do, I get this in my maillog:

    Name server: mo-net.com.: host name lookup failure

However, I can do the relevant looks manually:

    % whois mo-net.com | grep NS
       Registrar: NETWORK SOLUTIONS, INC.
       Name Server: NS.MO-NET.COM
       Name Server: NS2.MO-NET.COM
       NS.MO-NET.COM                12.14.225.10
       NS2.MO-NET.COM               12.14.225.11


    kirk at kanga:~% dig -t mx mo-net.com @12.14.225.10

    ; <<>> DiG 9.2.3 <<>> -t mx mo-net.com @12.14.225.10
    ;; global options:  printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 5268
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1

    ;; QUESTION SECTION:
    ;mo-net.com.                    IN      MX

    ;; ANSWER SECTION:
    mo-net.com.             259200  IN      MX      10 asmtp.mo-net.com.

    ;; AUTHORITY SECTION:
    mo-net.com.             259200  IN      NS      ns2.mo-net.com.
    mo-net.com.             259200  IN      NS      ns.mo-net.com.

    ;; ADDITIONAL SECTION:
    asmtp.mo-net.com.       259200  IN      A       12.14.225.18

    ;; Query time: 81 msec
    ;; SERVER: 12.14.225.10#53(12.14.225.10)
    ;; WHEN: Mon May 10 16:44:58 2004
    ;; MSG SIZE  rcvd: 101



    kirk at kanga:~% dig -t mx mo-net.com @12.14.225.11

    ; <<>> DiG 9.2.3 <<>> -t mx mo-net.com @12.14.225.11
    ;; global options:  printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24305
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1

    ;; QUESTION SECTION:
    ;mo-net.com.                    IN      MX

    ;; ANSWER SECTION:
    mo-net.com.             259200  IN      MX      10 asmtp.mo-net.com.

    ;; AUTHORITY SECTION:
    mo-net.com.             259200  IN      NS      ns.mo-net.com.
    mo-net.com.             259200  IN      NS      ns2.mo-net.com.

    ;; ADDITIONAL SECTION:
    asmtp.mo-net.com.       259200  IN      A       12.14.225.18

    ;; Query time: 70 msec
    ;; SERVER: 12.14.225.11#53(12.14.225.11)
    ;; WHEN: Mon May 10 16:45:01 2004
    ;; MSG SIZE  rcvd: 101


Now, I have noticed that this network's nameserver records are CNAMEs and
not As:

    kirk at kanga:~% dig -t any ns.mo-net.com @ns.mo-net.com

    ; <<>> DiG 9.2.3 <<>> -t any ns.mo-net.com @ns.mo-net.com
    ;; global options:  printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25013
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0

    ;; QUESTION SECTION:
    ;ns.mo-net.com.                 IN      ANY

    ;; ANSWER SECTION:
    ns.mo-net.com.          259200  IN      CNAME   pop3.mo-net.com.

    ;; AUTHORITY SECTION:
    mo-net.com.             259200  IN      NS      ns.mo-net.com.
    mo-net.com.             259200  IN      NS      ns2.mo-net.com.

    ;; Query time: 76 msec
    ;; SERVER: 12.14.225.10#53(ns.mo-net.com)
    ;; WHEN: Mon May 10 16:46:13 2004
    ;; MSG SIZE  rcvd: 82




    kirk at kanga:~% dig -t any ns2.mo-net.com @ns.mo-net.com

    ; <<>> DiG 9.2.3 <<>> -t any ns2.mo-net.com @ns.mo-net.com
    ;; global options:  printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12705
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0

    ;; QUESTION SECTION:
    ;ns2.mo-net.com.                        IN      ANY

    ;; ANSWER SECTION:
    ns2.mo-net.com.         259200  IN      CNAME   lacy.mo-net.com.

    ;; AUTHORITY SECTION:
    mo-net.com.             259200  IN      NS      ns.mo-net.com.
    mo-net.com.             259200  IN      NS      ns2.mo-net.com.

    ;; Query time: 69 msec
    ;; SERVER: 12.14.225.10#53(ns.mo-net.com)
    ;; WHEN: Mon May 10 16:46:20 2004
    ;; MSG SIZE  rcvd: 82


I've previously contacted the administrator of this network and he insists
loudly that he's been doing DNS for years and that there's nothing wrong
with his setup.  I don't *think* this is a Sendmail problem, since I process
thousands of emails per day through this system and I'm seeing the exact
same problem sending to this network from multiple hosts that I have access
to.

www.dnsreport.com also notices about the DNS records being CNAMEs, but even
though I know that's completely wrong, I'm not sure how it would cause the
problem.  Any ideas?
=2D-=20
Kirk Strauser
In Googlis non est, ergo non est.

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