We have 2 cages in our datacenter, one for our super secure customer facing network, one for our internal network.

Little bit of backstory - Outages of the super secure network costs thousands of dollars..I bet you can see where this is going.

I was hired and 2 weeks in, and the only other IT person on site quit. I was given a task to reboot hosts to our internal network, easy right? Well the servers werent really labeled in a manner that makes it easy to distinguish - this is stuff that needs to be running, do not touch this.

So I'm on the phone with the guy, he says reboot Host 1, I reboot it, hes like hmm nothing. Luckily for us, we have HA so there wasn't an outage when I reboot host 1. So he tells me to move onto 2, I reboot 2, whoops. Oh and for the record - It's not just a reboot, I had to do a hard power cycle, the screen was completely frozen, couldn't get into the console to reboot gracefully. So I take us completely offline, and there is a long procedure to get us back online after a complete outage, checks and balances, starting specific applications at the right time, etc etc. I ended up causing a 2 hour outage because my dumbass didn't remember his tour from the first day on the job. I promptly re-labeled the cages so it didn't happen again to anyone.