Niall O'Reilly <[email protected]> wrote: > > What's surprising is that an authoritative name server > shows both a decremented TTL value (as if it were answering > from cache) and the AA flag. > > I'm not sure which of the following labels is the best fit > for this behaviour: > > - normal and expected (but so far outside my experience), > - strange but harmless, > - downright wrong.
I would argue somewhere between the last two :-) During the IETF dnsop ANAME work I did some thinking about the TTL implications, and I realised that decrementing the TTL on an authoritative server would cause a thundering herd effect due to caches timing out at the same time. But I don't have any measurements that would indicate how much of a problem this is in practice... https://tools.ietf.org/html/draft-ietf-dnsop-aname-04#appendix-C Tony. -- f.anthony.n.finch <[email protected]> http://dotat.at/ Fitzroy: Southerly or southwesterly, 4 to 6, increasing 7 or gale 8 later in northwest. Moderate or rough, becoming very rough or high. Drizzle and fog patches. Good, occasionally very poor. _______________________________________________ dns-operations mailing list [email protected] https://lists.dns-oarc.net/mailman/listinfo/dns-operations
