In message <4a96bb45-eacb-4252-89c6-34061849c...@mac.com>, Chuck Swiger writes: > On Feb 14, 2012, at 2:16 PM, Mark Andrews wrote: > >> ISC's BIND has (or had) a MINTTL value of 5 minutes / 300 seconds. > >> It's probably unreasonable to expect other platforms to refetch DNS > >> records faster than that. > > > > To the best of my knowlege this is just plain wrong.
I stand corrected. This was changed in 4.9.3-beta27. It was also a protocol violation. 516. [proto] minimum TTL changes from five minutes to zero seconds. While ISC may have inherited it (BIND 4.8.3 was UCB CSRG code), we also fixed it. BIND 4.9.3 was the first release by ISC. A more complete history can be found at <http://www.isc.org/software/bind/history>. Mark > Look at BIND-4.8.3 and check named/db_update.c around line 40: > > int min_cache_ttl = (5*60); /* 5 minute minimum ttl */ > > ...and then: > > fixttl(dp) > register struct databuf *dp; > { > if (dp->d_zone == 0 && !(dp->d_flags & DB_F_HINT)) { > if (dp->d_ttl <= tt.tv_sec) > return; > else if (dp->d_ttl < tt.tv_sec+min_cache_ttl) > dp->d_ttl = tt.tv_sec+min_cache_ttl; > else if (dp->d_ttl > tt.tv_sec+max_cache_ttl) > dp->d_ttl = tt.tv_sec+max_cache_ttl; > } > return; > } > > ...or check named/ns_req.c around line 720 for the equivalent for a secondary > NS: > > if (dp->d_ttl) > ttl = dp->d_ttl; > else > ttl = zp->z_minimum; /* really default */ > #ifdef notdef /* don't decrease ttl based on time since verification */ > if (zp->z_type == Z_SECONDARY) { > /* > * Set ttl to value received from primary, > * less time since we verified it (but never > * less than a small positive value). > */ > ttl -= tt.tv_sec - zp->z_lastupdate; > if (ttl <= 0) > ttl = 120; > } > #endif > > Regards, > -- > -Chuck > -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
