Encontrou a resposta em Dicas do Mac OS X =)
I primarily work with web servers, and I use
lookupd -flushcacheall of the time to clear my DNS cache.This morning was moving some websites around using my newly-upgraded Mac, and I went to flush my DNS cache with
lookupdand I got a command not found error. It seems thatlookupdhas been removed in 10.5 and replaced withdscacheutil.So now I can flush my DNS cache with
dscacheutil -flushcache.