SOA minimum

[Brad Knowles]

At 4:15 PM +0700 5/22/01, Igor Podlesny wrote:

>        My  question  is about SOA minimum field -- more precisely about
>        it's  meaning.  Reading  appropriate  RFCs I found out, that the
>        third  and  the  last  at the moment meaning is TTL for negative
>        response caching.

	This is correct.  What used to be called the "Minimum TTL" within 
the SOA record is now used as a "Negative TTL", and the minimum TTL 
for the zone is set outside of the SOA, typically with a "$TTL" 
directive.

>        If  I  have  got  it correct it would be reasonable then to have
>        MINIMUM really low, and use adequate $TTL instead.

	You don't want to set the SOA "Minimum TTL" too low, because you 
do want nameservers around the world to cache for a reasonable amount 
of time the NXDOMAIN answers that your nameserver(s) hand out. 
Otherwise, this just unnecessarily increases the load on your 
nameserver(s).

	I would say that anything between five minutes and an hour would 
probably be a reasonable value for this number, depending on your 
exact circumstances, etc....

-- 
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,$_)}'