"Chris L. Morrow" <christopher.morrow@verizonbusiness.com> writes:
that sets a lower-bar on TTL in the nscd cache -
(from the manpage for nscd.con)
positive-time-to-live cachename value Sets the time-to-live for positive entries (successful queries) in the specified cache. value is in integer seconds. Larger values increase cache hit rates and reduce mean response times, but increase problems with cache coherence. Note that sites that push (update) NIS maps nightly can set the value to be the equivalent of 12 hours or more with very good perfor- mance implications.
This is still a client issue as, hopefully, the cache-resolvers don't funnel their business through nscd save when applications on them need lookups... (things like ping/telnet/traceroute/blah)
nscd may represent a problem if the application in question is a http-proxy without it's own resolver. There's also a number of more-or-less broken http-proxies doing their own resolver caching regardless of actual TTL. Such applications represent a problem wrt any DNS-based load balancing, including CDNs, since they can serve a large number of end-users, redirecting them to the "wrong" address long after the TTL should have expired. Bjørn