Fergie (Paul Ferguson) wrote:
Interesting thread on /. --
http://ask.slashdot.org/article.pl?sid=05/04/18/198259&tid=95&tid=128&tid=4
FWIW, I did some 'dig'ing on my Comcast home service. The DHCP is handing out 204.127.198.4 and 63.240.76.4 for DNS at the moment. I ran a query for a name in a zone I control that has a five minute TTL on 204.127.198.4. The first query came up with 5 minutes. I quickly made a change to the zone. hirty seconds after the initial query, I try again... err... and come up with the change. Hmm... Not caching at all? Another 30 seconds and I get the change, with 5m TTL. Thirty seconds later, I get the original response with appropriately decremented TTL. Another thirty seconds, I get the change, with 4m TTL. My findings: Comcast is now using some kind of load balancing that messes with this kind of testing. 204.127.198.4 is not a single resolver. However, as far as I could tell, they were obeying the TTL. After 5 minutes, all of the responses were coming back with the change. The TTL values in the responses were decrementing as expected. -- Crist J. Clark crist.clark@globalstar.com Globalstar Communications (408) 933-4387