telnet:25 on the right DNS entry ???

Edmund c990077 at hk.china.com
Thu Dec 2 02:43:18 UTC 1999


Oh, no, too technical, if someone understand what's MX, he probably wouldn't
have ask such a question.  Please redirect him to http://www.dns.net for DNS
concept first.

Mathias Koerber wrote:

> It's called an MX record. Every SMTP server is supposed to look up
> MX records to find where to deliver email for a certain domain.
> Most Mail clients (MUAs) don't have this functionality, which is why they
> require a fixed SMTP server to take on this task for them.
>
> HTH HAND
>
> $ dig usa.net mx
>
>     ; <<>> DiG 8.1 <<>> usa.net mx
>     ;; res options: init recurs defnam dnsrch
>     ;; got answer:
>     ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
>     ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3
>     ;; QUERY SECTION:
>     ;;      usa.net, type = MX, class = IN
>
>     ;; ANSWER SECTION:
>     usa.net.                53S IN MX       10 mxpool01.netaddress.usa.net.
>
> (so your guess was even correct, unless mail.usa.net is physically
> the same machine).
>
>     ;; AUTHORITY SECTION:
>     usa.net.                53S IN NS       dns01.ops.usa.net.
>     usa.net.                53S IN NS       dns02.ops.usa.net.
>
>     ;; ADDITIONAL SECTION:
>     mxpool01.netaddress.usa.net.  22m15s IN A  204.68.24.19
>     dns01.ops.usa.net.      20h42m33s IN A  204.68.24.137
>     dns02.ops.usa.net.      9h10s IN A      204.68.24.134
>
>     ;; Total query time: 11 msec
>     ;; FROM: venus-flytrap to SERVER: default -- 165.21.83.88
>     ;; WHEN: Thu Dec  2 07:14:19 1999
>     ;; MSG SIZE  sent: 25  rcvd: 153
>
> -----Original Message-----
> From: newsgroups <catto at qwestinternet.net>
> Newsgroups: comp.protocols.dns.bind
> To: comp-protocols-dns-bind at uunet.uu.net
> <comp-protocols-dns-bind at uunet.uu.net>
> Date: Thursday, December 02, 1999 12:59 AM
> Subject: telnet:25 on the right DNS entry ???
>
> |example: myemail at usa.net
> |I tried randomly until I found that to use telnet on the port 25(smtp) the
> |right address is NOT usa.net but it is mail.usa.net instead...
> |how should a software understand it????
> |
> |again: it I do telnet usa.net 25 IT WON'T WORK !!!
> |I manually guessed mail.usa.net 25 and it's fine but the PC does now
> |guess...
> |what C/C++ function returns or redirects to the right DNS entry ???
> |
> |



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