[Manal]

i think manal knows about these pages and read it already. he wants to know if anyone around here has more in depth knowledge on what goes on behind the scene in that anti-ddos setup.
may be hr knows better.

i can just hazard some guesses. they have terabyte scale capacity
at the backbone.
i guess they sample data packets.. say one in every 2000 or some such using highly parallel processing systems
using specialised processors (not general purpose ones..for better speed and efficiency).
now ddos attacks are mostly dumb. like same or similar kind of connection/page requests without further interactions with that requested page. so if the system sees lots of similar and repeated requests from zillions of different ips then it can start dropping the packets from those source ips and thus kill the flood even from entering the Gbps and Mbps scale networks.

i dunno

Agreed with you @rudra. I have read the article but still, they haven't mentioned exactly how they tackle the attacks. Your predictions might be true with what you say.