Have you ever found yourself having a hard time loading a website and you know you that it should be loading? Chances are you will need to flush your DNS on your machine.
sudo discoveryutil udnsflushcaches
dscacheutil -flushcache; sudo killall -HUP mDNSResponder
OSX 10.7 – 10.8
sudo killall -HUP mDNSResponder
OSX 10.5 – 10.6
sudo dscacheutil -flushcache