% dig MX ns.yp.to
; <<>> DiG 9.3.4 <<>> MX ns.yp.to
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 59696
NXDOMAIN but the domain exists:
% dig ANY a.ns.yp.to
...
;; ANSWER SECTION:
a.ns.yp.to. 259200 IN A 131.193.36.25
This particular case happens to be misconfigured glue; the only place
where a.ns.yp.to exists is in the servers for to., not yp.to. That's
typical of this kind of breakage.
A reasonable question is in how many cases does such a domain want to
send or receive mail. I would be surprised if the number were greater
than zero; I would be astonished if the number were large enough to
care about.
Every spec is misimplemented somewhere. If you make perfect
implementations of something a prerequisite, you'll never be able to
do anything.
Regards,
John Levine, johnl(_at_)iecc(_dot_)com, Primary Perpetrator of "The Internet
for Dummies",
Information Superhighwayman wanna-be, http://www.johnlevine.com, ex-Mayor
"More Wiener schnitzel, please", said Tom, revealingly.
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