Bug in bind? MX and no A record

[Jim Reid]

    >> Hi..  I've been debugging an email problem.  A domain
    >> (example.com) has an MX record but no A record.

    >> # dig example.com mx
    >>   * this works 
    >> # dig example.com
    >>   * this says 'NXDOMAIN'
    >> # dig example.com mx
    >>   * now this says 'NXDOMAIN', but it worked 2 seconds ago!?

    >> Reproducible?  Real bug?  Design feature?  Let me know.

Try providing real information instead of this example.com crap.

How do you expect anyone to help you while you deliberately conceal
and obfuscate the facts? Provide the actual domain name and the full
output from each dig query. In other words, don't post your summary of
what you think happened. Show us *exactly* what dig is saying. Tell us
the truth, the whole truth and nothing but the truth.