They have skill quizes and I keep scoring in the top 30%, even though I'm a complete idiot.
@makeworld Let's hypothetically say you're a web developer, running a local web server.
Now any ad network (or attacker that can influence DNS requests) can target your local web server.
Either way, if an attacker can coerce your system to looking up a specific record, your attacker can now target your local computer.
Remember, folks, if your DNS-based adblocking mechanism returns 0.0.0.0 or 127.0.0.1, attackers can use that to their advantage.
Either return NXDOMAIN or NOERROR (aka, no results) instead.