Pi Holes
 

How good are these at really killing ads?



https://pi-hole.net/

It's a DNS server. It can block any address which is used for ads. I haven't researched this particular implementation, but I've used custom DNS for this purpose in the past. I've also used inline request filtering which is more effective.



Essentially how this works is your computer makes a request to ad.com and this returns a black hole domain, so you never see the ad.