>> looks like ph10's guess was correct, the A is being returned before the
>> AAAA. i suspect my v6 friends would ask that AAAA be preferred even if
>> it is not first.
>I presume you mean in the case
> MX -> name -> two IP addresses, one v4 and one v6
>but not in the case
> MX -> two names, one has A and one has AAAA
>where of course the MX preferences will determine the order.
>Is it worth adding an option to Exim specially for this, when your v6
>friends can achieve what they want by suitable MX records? I need more
>convincing...
yes, this is the former case. other IPv6-ready applications (like
telnet, ftp, ssh, whatever) uses IPv6 first when a name resolves to
multiple addresses with mixed IPv6 ones and IPv4 ones. the methodology
is good for transition (otherwise, we'll keep using IPv4 and transition
never happens even if dual stack servers get deployed...).
itojun
% dig iijlab.net. mx
; <<>> DiG 9.1.2 <<>> iijlab.net. mx
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63814
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3
;; QUESTION SECTION:
;iijlab.net. IN MX
;; ANSWER SECTION:
iijlab.net. 3600 IN MX 10 sh1.iijlab.net.
;; AUTHORITY SECTION:
iijlab.net. 3600 IN NS dns0.iij.ad.jp.
iijlab.net. 3600 IN NS sh1.iijlab.net.
;; ADDITIONAL SECTION:
sh1.iijlab.net. 3600 IN A 202.232.15.98
sh1.iijlab.net. 794 IN AAAA 2001:240:0:200:260:97ff:fe07:69ea
sh1.iijlab.net. 794 IN AAAA 3ffe:507:0:1:260:97ff:fe07:69ea
;; Query time: 56 msec
;; SERVER: 127.0.0.1#53(0.0.0.0)
;; WHEN: Thu Apr 18 19:19:15 2002
;; MSG SIZE rcvd: 162
% dig sh1.iijlab.net. aaaa
; <<>> DiG 9.1.2 <<>> sh1.iijlab.net. aaaa
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31628
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;sh1.iijlab.net. IN AAAA
;; ANSWER SECTION:
sh1.iijlab.net. 779 IN AAAA 3ffe:507:0:1:260:97ff:fe07:69ea
sh1.iijlab.net. 779 IN AAAA 2001:240:0:200:260:97ff:fe07:69ea
;; AUTHORITY SECTION:
iijlab.net. 3585 IN NS dns0.iij.ad.jp.
iijlab.net. 3585 IN NS sh1.iijlab.net.
;; ADDITIONAL SECTION:
sh1.iijlab.net. 3585 IN A 202.232.15.98
;; Query time: 5 msec
;; SERVER: 127.0.0.1#53(0.0.0.0)
;; WHEN: Thu Apr 18 19:19:30 2002
;; MSG SIZE rcvd: 146
% dig sh1.iijlab.net. a
; <<>> DiG 9.1.2 <<>> sh1.iijlab.net. a
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 64978
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
;; QUESTION SECTION:
;sh1.iijlab.net. IN A
;; ANSWER SECTION:
sh1.iijlab.net. 3573 IN A 202.232.15.98
;; AUTHORITY SECTION:
iijlab.net. 3573 IN NS dns0.iij.ad.jp.
iijlab.net. 3573 IN NS sh1.iijlab.net.
;; ADDITIONAL SECTION:
sh1.iijlab.net. 767 IN AAAA 3ffe:507:0:1:260:97ff:fe07:69ea
sh1.iijlab.net. 767 IN AAAA 2001:240:0:200:260:97ff:fe07:69ea
;; Query time: 5 msec
;; SERVER: 127.0.0.1#53(0.0.0.0)
;; WHEN: Thu Apr 18 19:19:42 2002
;; MSG SIZE rcvd: 146
