On Tue, Jan 26, 1999 at 11:19:32PM +0100, Rask Ingemann Lambertsen wrote:
> On 18-Jan-99 05:51:16, Chris Johnson wrote something about "Re: Three solutions for
>spam". I just couldn't help replying to it, thus:
>
> > I've always wondered why Dan doesn't have an MX record for koobera (though
> > it doesn't really matter now that we're supposed to be using list.cr.yp.to).
> > An A record is all that's required to get the mail delivered, but if there
> > were an MX record my name server would cache it, rather than making a query
> > in vain for a non-existent MX record every time a message needs to go there.
>
> There is such a thing as caching of negative replies. Correct me if I'm
> wrong, but IIRC, BIND does so.
I think recent versions of BIND do cache negative replies, but only for a very
short time. I don't have any documentation handy, but I think it's only for ten
minutes. So having an MX record, even if you already have an A record, would
cut down on name server queries.
Chris
