DNS stuff (was Re: [olug] Cox and Web Servers)

[Phil Brutsche]

Brian Wiese wrote:
> On Tue, 8 Oct 2002 21:07:42 -0500 (CDT)
> Phil Brutsche <phil at brutsche.us> wrote:
> 
> 
> |Almost any port # you want (don't choose stuff like 25, 137-139, 111,
> |etc), and yes.
> 
> this is that SRV stuff?

RFC #2782 - "A DNS RR for specifying the location of services".

It let's you do stuff like this (this is a BIND-style DNS zone file, for 
those not-quite-in-the-know):

$ORIGIN .
$TTL 43200
example.com IN SOA ns01.example.com. admin.example.com. (
              200210090201
              14400
              3600
              604800
              43200)
             IN NS ns01.example.com.
             IN NS ns02.example.com.

$ORIGIN example.com.
_smtp._tcp IN SRV 10 10 10025 1.2.3.4

Which says that the host at 1.2.3.4 handles SMTP for the domain 
example.com on port 10025.

There's another example on the last page of RFC #2782.

MS ActiveDirectory and Apple's directory services are just about the 
only people who use SRV records; its part of their auto-detection of 
network services.

MTA, telnet & ssh clients, web browsers, and many other clients, would 
benefit from knowing how to use them, but, alas, none do.