ddos is a very broad category of attacks, so there isn't one single solution. What really matters, is that you have some sysadmin type on board who knows his network protocols.
I personally got hit with a flood of many small packets, which overwhelmed my router. The obvious solution here is to buy a better router. (it was 200Mbps of rather small packets on a 1000Mbps pipe.) I ended up just having my upstream blackhole all traffic to the target IP, which is sad, as it 'finishes the job' for the attacker, but on a $12/month account, what do you want?
Now, for what I provide (VPS hosting) an application-level DoS, slowlaris or just hitting your app in an expensive way isn't really my problem. That's on the application programmer, and as this is mostly a form for application programmers, it does make sense that the highest modded comments on this page describe mostly application level DoS mitigation strategies.