If you mean a denial of service attack, as per grc.com it is a:
Distributed Reflected Denial of Service,
basically a near impossible to trace DDOS attack bounced around through different computers, keeping the source concealed (after all the attacks are just from infected machines, not said attacker) or something like that. Been a while.
I read his article here a while ago:
http://grc.com/dos/drdos.htm