Re: DNS based Destination Selection

[Jay Ford <jay-ford@uiowa.edu>]

On Thu, 19 Jun 2003, Cedric de Launois wrote:
> My question is : what is the goal pursued with this mechanism ?
> - If the goal is to perform inbound traffic engineering, then I'd say
>   this mechanism is not sufficient. Not enough traffic is controlled via
>   this way to get good load-balancing.

Agreed.  Further, if the choice of source address preempts the path
selection, then the TE intended by the DNS preferences don't work.

> - If the goal is just to somewhat improve an external source's
>   destination decision making, then what is the advantage of your
>   suggestion compared to just carefully ordering the list of addresses
>   returned in the DNS reply (solution which doesn't imply any change in
>   the hosts) ?

DNS replies often don't go directly from DNS server to DNS client when they
are in different administrative domains.  Recursive queries, caching,
secondary service... all introduce places where the RRs can get reordered.

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford@uiowa.edu, phone: 319-335-5555, fax: 319-335-2951