Tom Jordahl is a Macromedia Server Development Engineer and he’s just blogged about CFHTTP caching DNS Queries.
Apparently people were blaming the CFHTTP tag for caching the DNS queries forever, or at least until you restarted the CFMX services.
Tom did some digging and found the culprit is actually the JAVA InetAddress class (which MM uses to support HTTP operations). He provides a tweak to fix this and hopes to get a technote etc published.
And thanks to Talking Tree aka Steven Erat for the heads up.