On Tuesday 10 August 2004 1:40 pm, Ted Hardie wrote:
Both records do _not_ contain the same information. The first
record has a target of MAIL_FROM; the second has a target
of PRA. The fact that the strings "a mx ptr" happen to be
the same in both records does not change that fundamental
fact. The fact that the same IPv4 dotted quad might appear in
an MX record and NS record for example.com doesn't change
the fact that the records tell you different things about how
that domain's systems are set up. The situation here is
parallel; it isn't as obvious because you're using the overloaded
TXT record rather than the new RR.
Just as an annoying DNS nit: IPv4 dotted quad addresses in MX or NS records
are misconfigurations (in the MX case, this is somewhat common, but it is
still wrong). The targets of MX and NS records are DNS names, not IP
address. Those names then map to IP addresses via A or AAAA records.
Not that this diminishes Ted's point.
--
David Blacka <davidb(_at_)verisignlabs(_dot_)com>
Sr. Engineer VeriSign Applied Research