[ On Wednesday, February 10, 1999 at 10:56:28 (+0000), Philip Hazel wrote: ]
> Subject: Re: [EXIM] Multiple PTR records for a Reverse DNS lookup
>
> On Tue, 9 Feb 1999, Kevin P. Fleming wrote:
>
> > I've got a vendor who sends me email, which is bounced because the forward
> > and reverse lookups for his outbound SMTP server don't match... However,
> > there are _three_ PTR records for his server's IP address (which is a
> > no-no),
Nope. In fact it's recommended in the necessary circumstances. See RFC 2181.
> > and two of them work, one of them doesn't. I've contacted them and
> > told them this needs to be corrected, but should Exim do anything
> > differently in this case? Or does it even get enough information back from
> > gethostbyaddr() to be able to do anything different?
>
> The interface to gethostbyaddr() is capable of returning only a single
> host name.
Nope, at least this is not a problem with relatively modern DNS resolver
implementations. This is what the "h_aliases" list is for.
struct hostent {
char *h_name; /* official name of host */
>>>> char **h_aliases; /* alias list */
int h_addrtype; /* host address type */
int h_length; /* length of address */
char **h_addr_list; /* list of addresses from name server */
};
(Strictly speaking there is no such thing as an "official" name of a
host. In theory all names are equivalent. In fact I believe that
modern implementations may return a "random" name in h_name.)
--
Greg A. Woods
+1 416 218-0098 VE3TCP <gwoods@???> <robohack!woods>
Planix, Inc. <woods@???>; Secrets of the Weird <woods@???>
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