I have a NetBSD 1.6/i386 IPv6 system and sendmail was unable to
send an email to vtext.com (Verizon Wireless cell phone).

If I 'telnet smtp.css.vtext.com smtp', I get "No address associated
with hostname.".

A 'dig smtp.css.vtext.com a' terminates with no error.

If I 'dig smtp.css.vtext.com aaaa ; dig smtp.css.vtext.com a'; the
second query terminates with NXDomain.  These two queries mimic
the behavior of telnet.

The name "smtp.css.vtext.com" has a TTL of zero seconds.  I have
seen small TTLs, but never zero.

Any ideas?

A query of the AAAA and then A record:

tcpdump -n -i ethernet
13:57:02.528605 153.60597 > 66.174.3.4.53:  7805 AAAA? smtp.css.vtext.com. (36)
13:57:02.673878 66.174.3.4.53 > 153.60597:  7805 NXDomain- 0/0/0 (36)

tcpdump -n -i lo0
13:57:02.526529 33.60198 > 33.53:  2+ AAAA? smtp.css.vtext.com. (36)
13:57:02.674522 33.53 > 33.60198:  2 NXDomain 0/0/0 (36)
13:57:02.695074 33.60197 > 33.53:  2+ A? smtp.css.vtext.com. (36)
13:57:02.698792 33.53 > 33.60197:  2 NXDomain 0/0/0 (36)

A query of just the A record:

tcpdump -n -i ethernet
13:58:33.851177 153.60597 > 66.174.3.4.53:  56935 A? smtp.css.vtext.com. (36)
13:58:34.001277 66.174.3.4.53 > 153.60597:  56935*- 1/0/0 A 66.174.3.10 (52)

tcpdump -n -i lo0
13:58:33.849093 33.60196 > 33.53:  2+ A? smtp.css.vtext.com. (36)
13:58:34.002042 33.53 > 33.60196:  2* 1/0/0 A 66.174.3.10 (52)

-- 
John D. Smerdon                      jds at smerdon.livonia.mi.us
Livonia, Michigan, US