[dreamins]

Geo DNS (to be more precise AS numbers is what is used) is something that is sometimes used as a very last resort - customers in China are customers as well, and if you drop everything from China thats effectively what the attacker wanted.

I recall only hearing about one time when packets from Chinese ISPs were completely dropped for some reason and only for short period.

I've also have an anecdotal reference that one can persuade providers that actually deliver traffic from China to do filtering on ingress on next hop routers after China, but that should be something very serious, that impacts their revenue as well and prolonged. As another commenter noted - costs for providers are very non-trivial.

In my experience DDOS is always money competition, it costs money to mount one, it costs money to defend against one. Unfortunately when one of the sides is [allegedly] a country it doesn't play very well.