So this morning I was doing some work with one of my webservers and adding new sub hosts to some of the domains and to see the changes on my MacBook pro laptop I knew I would need to flush the DNS cache so I wouldnt have to wait for the cache to expire.

So for anyone else who needs to know the commands here they are:

OS X <= 10.5.1

lookupd -flushcache

OS X >= 10.5.2

dscacheutil -flushcache

Hope that will help anyone out there who needs to flush their dns cache and has just upgraded to 10.5.2