- Published on Monday, 24 September 2012 21:56
Normally I wouldn't post something relatively trivial like this. However it came to my attention today that the Mac OS X may cache out-of-date DNS entries as long as the record is still valid according to its TTL. I might not expect this behavior because the Mac is not running a DNS server and its resolv.conf points to an authoritative DNS server that is serving up-to-date data.
I would expect a copy of BIND or another caching DNS server to cache old records until the TTL expires, but not a normal network OS running a resolver client with a resolv.conf file etc. I'm running Mac OS X 10.6.8. Anyway, to clear the DNS cache on my mac, I typed this:
$ dscacheutil -flushcache
Curiously a google search of "mac os x flush dns" did not turn up that simple command, so I'm putting it on my blog for posterity.