Subject: RE: DNS resolution hints

From: "Art Shelest" <[email-masked]>
Date: Tue, 23 Apr 2002 08:56:33 -0700

Jim:

Thank you for pointing out the option that didn't make on the list of
workarounds:

* an application speficic option

Pros: does not require DNS changes.
Cons: needs to be implemented for every application that requires
testing or troubleshooting. Cannot be implemented for apps that do not
call getaddrinfo directly, such as apps using RPC, or any connectivity
library.

This is the solution used by ping, tracert and pathping, currently
implemented in WinXP.
For example, ping -6 www.example.com will only use IPv6 address.

One cannot make this work for Outlook (uses RPC) or IE (uses generic
HTTP system API).

Thanks!

-----Original Message-----
From: Jim Reid [mailto:[email-masked]] 
Sent: Tuesday, April 23, 2002 1:09 AM
To: Art Shelest
Cc: [email-masked]
Subject: Re: DNS resolution hints 

>>>>> "Art" == Art Shelest <[email-masked]> writes:

    Art> Problem: When testing or troubleshooting applications, it's
    Art> useful to isolate a single protocol. With a hostname
    Art> resolving to both A and AAAA, there's no telling which
    Art> address and which protocol will be used for communication.

Surely that's a decision for the application that made the lookup? This
is no different from a query which returns a bunch of IP addresses
because the name being looked up is for a multi-homed host: which one
does the application use? Policy issues like this shouldn't get "solved"
in the DNS. They don't belong there. Presumably the application could be
given selection criteria through something like a configuration (file)
option or environment variable or, since you're from Redmond, a registry
setting.

--
to unsubscribe send a message to [email-masked] with
the word 'unsubscribe' in a single line as the message text body.
archive: <http://ops.ietf.org/lists/namedroppers/>

---

From: Danny Mayer <[email-masked]>
Date: Wed, 24 Apr 2002 00:08:07 -0400

>One cannot make this work for Outlook (uses RPC) or IE (uses generic

Since Microsoft owns these applications, there is nothing to prevent you from
modifying the application to check the registry for such a flag or include it
on the command line when it is started. Assuming that Microsoft is going to
be using the SRV records for looking up available services, you should be
able to set up the SRV record to point to either v4 or v6 addresses only.

         Danny