is bind needed at all?

[Kevin Darcy]

Everton da Silva Marques wrote:

> Will Yardley wrote:
> >
> > Chris Thomas wrote:
> > > Use of MX records is also a performance issue.  If you omit an MX record
>
> > > for A record site that receives mail, you force senders to make a
> useless
> > > MX query to the receiving nameserver before requesting the A record,
> > > which may be (is probably) cached locally to the sender.  (Name servers
> > > that cache the non-existance of MX records mitagate this.)
> >
> > although to be fair, i believe in actual practice, most mail servers,
> > including sendmail, make the first query for records of type 'ANY' not
> > for an 'MX' specifically, even though in an ideal world, they would
> > probably query for an MX first.  i think it's more efficient to just
> > query for ANY in the first place.
>
> A quick-and-dirty inspection of Postfix and Sendmail seems to indicate
> otherwise:
>
> >From postfix-20010228-pl04/src/smtp/smtp_addr.c:
>
>   /* smtp_domain_addr - mail exchanger address lookup */
>   DNS_RR *smtp_domain_addr(char *name, VSTRING *why, int *found_myself)
>   {
>     ...
>     switch (dns_lookup(name, T_MX, 0, &mx_names, (VSTRING *) 0, why)) {
>     ...
>   }
>
> >From sendmail-8.11.6/sendmail/domain.c:
>
>   /* bestmx_map_lookup() calls getmxrr() */
>
>   getmxrr(host, mxhosts, mxprefs, droplocalhost, rcode)
>   ...
>   {
>     ...
>     n = (*resfunc)(host, C_IN, T_MX, (u_char *) &answer, sizeof(answer));
>     ...
>   }

Sendmail 8.11.x uses T_ANY for "canonicalization" queries. See the
dns_getcanonname() routine in domain.c

As I posted earlier, as of sendmail 8.12, T_ANY queries will no longer be used.


- Kevin