Search Again: Re: DNS Cashing From: Men & Mice Support Date: Friday, November 5, 1999 Time: 12:07:00 am At 5:40 PM -0600 11/4/99, Dennis J. Bonsall, Jr. wrote: >I have a quick question. I understand that this program "QuickDNS" >Provides load sharing and when a server is down, it will redirect all >traffic the the server that is still up. My question is how will it >perform with cached entries on other DNS servers. Example: > >At 2:00 PM a user on AOL access www.mydomain.com and AOL's DNS caches >xxx.xxx.xxx.201. >At 4:00 PM the server on xxx.xxx.xxx.201 crahses thus causing the >routing to be directed to xxx.xxx.xxx.202. >At 4:30 PM another user on AOL requests www.mydomain.com and AOL's DNS >reports that xxx.xxx.xxx.201 is the IP. > >How do you get the DNS server at AOL to remove the entry from their >cache to report xxx.xxx.xxx.202 as the server? >Are you stuck with all AOL users using AOL's DNS servers hitting the >dead IP until their DNS' cache gets flushed at midnight? In theory, they aren't supposed to cache a record for longer than the time specified in the TTL (time-to-live). The default TTL on a load balance record is 300 seconds, or 5 minutes. Some people use lower values, even including 0. In reality, there are some caching DNS resolvers that don't follow the rules. AOL's is rumored to be one of them. There's nothing we can do about that except complain to them. ____________________________________________________________________ Chris Buxton cbuxton@menandmice.com Men & Mice http://www.menandmice.com Makers of: QuickDNS Pro

Messages In This Thread: DNS Cashing by Dennis J. Bonsall, Jr. on Nov 4, 1999 at 11:40:00 pm Re: DNS Cashing by Men & Mice Support on Nov 5, 1999 at 12:07:00 am