Just spend a while scratching my head over this one.. if you are using Cisco AnyConnect on Mac OSX and are using static entries in your /private/etc/hosts file, it will overwrite them with /private/etc/hosts.ac in versions 3.0.4 and earlier. This was fixed in
3.0.5080 - Release Notes
CSCts72767 3.0.4 AnyConnect overwrites hosts file by hosts.ac
