Built successful automation and support tools that maintained a very profitable 3.5 9s on self-hosted bare metal.
From me as an IC, this involved numerous areas of automation and development but my favorite was a network failover issue that cropped up that would have involved replacing all of our networking hardware. Within a week, I'd diagnosed the issue and built a suite of tools utilizing an external observer sending specially formed packets through a conditional routing system to detect route failure and initiate a failover procedure (I mean really, who are we kidding? This part was really just a script with a lot of ip route commands but failover procedure sounds pretty neat.)
The best part is that this tool is still in use and has, to this day, been the only automated failover mechanism that didn't us fail at some point (though just like the OpenBSD webpage, that will eventually not be true). It's preserved millions in revenue so far and I'm pretty proud of that fact.Describe the most impressive thing you've done.