Name Server Timeout and Sendmail

[Neil Rickert]

kemper at tstar.net (Butch Kemper) writes:

>My customers are having troubles sending email to axs4u.net accounts. 
>When I look in the mailq, I find the messages with this error message:

>     Deferred: Name server: mail.axs4u.net.: host name lookup fail

>Using dig, I have found that:

>   1.  Asking for the mx records for axs4u.net returns no data just a
>       status: SERVFAIL.

That would cause the timeout.

>   2.  After locating the NS for the domain, I queried for the mx records
>       and found:

>              axs4u.net.              1D IN MX        10 mail.axs4u.net.

>   3.  Asking the NS for any information about mail.axs4u.net, I found:

>              mail.axs4u.net.         1D IN CNAME     axs4us02.axs4u.net.

The names on the RHS of MX records are not supposed to be CNAMEs.

>   4.  Asking the NS for any information about axs4us02.axs4u.net, I found:

>              axs4us02.axs4u.net.     1D IN MX        10 mail.axs4u.net.
>              axs4us02.axs4u.net.     1D IN A         207.211.104.222

>This appears to be a circular defination and that is why Sendmail is
>giving the error message?

It is not circular, but it is a bad MX pointing to CNAME.

>So, are the DNS definations at axs4u.net incorrect or is there something
>wrong at my end?

>On other thing, AOL seems to be able to send mail to users at axs4u.net.

Older nameservers are more forgiving of these errors than newer ones.