Which isn't near the issue that application-level caching is.  It seems to be slowly getting better, but I've seen numerous apps (especially in embedded space) cache resolved addresses seemingly forever.  We found this at my day-job when dealing with dns-based failover between servers.

I greatly prefer to disable application-layer caching entirely, and rely on a central caching resolver like dnsmasq in those environments (where we're running local to dnsmasq, so it's very fast).

-Aaron