Some of the more entertaining defenses I've seen are netting and actual hawks trained to snatch them out of the sky!

Nets tend to be a sort of one-hit thing, so if you miss you're out of luck. They're obviously not ideal around airports and other infrastructure.

well up until the point where it is an aerosol attack. protection is probably going to be down to specialized sensor arrays and some form of ballistic counter but these solutions will be expensive and harder to deploy than the attack.

drones open the door to all sorts of malfeasance that used to require state level backing to accomplish and counters are only coming into play if not concept