h2n utility

Kevin Darcy kcd at daimlerchrysler.com
Thu Jan 27 23:44:24 UTC 2000


Eddy Kalem wrote:

> I noticed that when I run the h2n utility it generates an MX record for
> every A record. Does this have to be or am I doing something wrong?

I suspect that this was done deliberately as an optimization: if a mail
server does an MX record query and gets no answers, it then has to do an
A record query. That's two queries. But if every A record automagically
has an accompanying MX record, then it only has to do the MX query (the A
record is then typically supplied in the "additional" section of the
response), and the total number of queries is cut in half. In theory. More
recent versions of sendmail deal with the problem by doing an ANY query,
thus obtaining both types of records, but older versions, or other
mailers, may still be using the old-fashioned method.

According to the h2n documentation, you can suppress the MX record
generation with the -M option.


- Kevin




More information about the bind-users mailing list