i realize this is apolitical and offtopic. i apologize in advance. geoff's improvements in dns are really quite nice. dns appears do a good job in the face of well-behaved servers, but there are some ill behaved ones for popular sites that give me occasional fits.
for example, www.apple.com decided to disappear last evening. i looked into the problem and nserver*.apple.com were not reachable. and the reason the local nameserver didn't have www.apple.com cached is that the ttl of www.apple.com is 60 seconds. interestingly, a dsl modem we have here continued to resolve www.apple.com during this time, though it also couldn't reach the nameserver. it seems that the dsl modem's resolver or upstream cache was just serving up a stale rr. this is a common problem around here (esp.) for akadns-served sites with very low ttls. i'm thinking it would make sense to either (in order of increasing preference andimplementation difficulty ) a) ignore very short, but nonzero, ttls and make them at least 3600s. b) serve up stale rrs if a fresh answer isn't available up to some multiple of the real ttl. c) activly refresh the "most active" cache entries starting at 1/2 the ttl and increasing in frequency until some mutiple of ttl has expired. - erik
