BIND9.2.0a2 Source Code

[Brad Knowles]

At 12:14 PM +0530 7/25/01, Vaishali Paithankar wrote:

>  In fact, I wanted to do load balancing of the servers which are
>  geographically distributed. In this case we need to have metrics which
>  take into consideration the geographically distributed nature of the
>  servers.

	I still say that you should be using load-balancing switches and 
anycasting of addresses.

>  Since, the DN System already has a distributed structure, this property of
>  DN System can be used to make decision to choose the server.

	Just because the nameservers are distributed does not necessarily 
mean anything about the application servers that are also distributed.

>  The DN Server would do the metric collection of e.g. RTT. This
>  DN Server is assumed to be the nearest to the client to which
>  the client has sent the query for I.P. address of the web site. So now,
>  the client gets a good idea of the performance of all the servers
>  depending upon client's geographical location.

	The RTT from the nameserver to the application server may very 
well be meaningless.  The server itself could be fine and respond 
very quickly to probes, but the application may well be hosed.  You 
need to monitor at a higher level than that, and to get an accurate 
picture, you need to monitor the connections on a much more frequent 
basis -- preferably on a connection-by-connection basis, which is 
precisely what a good load-balancing switch does.

>  Instead of making changes in the zone files (RRs), is it possible to
>  add/update the metrics in the memory where the zones are loaded (this was
>  the reason to make changes in the source code) so that it not necessary to
>  load the zones as and when we want to update the metrics ?

	Not in any way I know of, no.  This is why I keep going back to 
using load-balancing switches for the job that they were designed to 
do, as opposed to mis-using and abusing the DNS to try to do this.

-- 
Brad Knowles, <brad.knowles at skynet.be>

/*        efdtt.c  Author:  Charles M. Hannum <root at ihack.net>          */
/*       Represented as 1045 digit prime number by Phil Carmody         */
/*     Prime as DNS cname chain by Roy Arends and Walter Belgers        */
/*                                                                      */
/*     Usage is:  cat title-key scrambled.vob | efdtt >clear.vob        */
/*   where title-key = "153 2 8 105 225" or other similar 5-byte key    */

dig decss.friet.org|perl -ne'if(/^x/){s/[x.]//g;print pack(H124,$_)}'