On Thursday 07 October 2004 22:23, Nate Duehr wrote: > - They don't understand that there might be multiple DNS servers between > their top-level and the machine they're servicing (3X and 4X TTL)
Let's say that I have my local (desktop if you prefer) resolver (which I'll call A is pointed to a caching nameserver B. Caching nameserver B forwards all of it's DNS requests to their ISP's larger caching server C. Caching server C makes queries to the appropriate authoritative server D. So the DNS query goes: A->B->C->D D replies to C with a record having TTL of 3600. C forwards request to B, B gives answer to A ... TTL 3600. In 1800 seconds the only server in the above loop that would serve a TTL of 3600 is D (since it is authoritative). B and C will both have decremented their TTL by 1800 seconds and will respond with a TTL of 1800 seconds. A should have decremented the TTL in it's resolver cache as well though some applications and/or operating systems are buggy in this regard. I have never seen behaviour that you are suggesting can happen nor can I imagine any way in which it can happen. We had a similar discussion not too long ago starting at http://www.mail-archive.com/debian-isp%40lists.debian.org/msg11986.html ... I never really followed up on that one, but I still believe you're wrong ;-) BTW, forwarding (to an appropriate server) is an excellent way to speed up DNS resolution, I use it frequently. -- Fraser Campbell <[EMAIL PROTECTED]> http://www.wehave.net/ Georgetown, Ontario, Canada Debian GNU/Linux -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]