On Feb 14, 2012, at 11:11 AM, Alan Clegg wrote: > On 2/14/2012 1:42 PM, Chuck Swiger 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. > > Uh... no. BIND has always respected TTL when caching information.
See http://www.ietf.org/rfc/rfc1035.txt "The MINIMUM value in the SOA should be used to set a floor on the TTL of data distributed from a zone. This floor function should be done when the data is copied into a response. This will allow future dynamic update protocols to change the SOA MINIMUM field without ambiguous semantics." ...and lib/dns/master.c dns_soa_getminimum() and limit_ttl(). At one point, and I might be dating myself back to the BIND-4.x days, these used to set a minimum floor value of 300 seconds, even if the SOA or per-record TTL was smaller. Maybe that is no longer the case in BIND-9.x and more common use of dynamic updates, but I repeat my observation that it's not reasonable to update DNS at sub-minute intervals and expect all clients to honor such.... Regards, -- -Chuck _______________________________________________ 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
