Recommendations for « practical » study resources that’d help in a Managed Services role

Hi,

Day to day I face issues where something doesn’t work in large, sparsely documented environment, and I’ve only limited information / piece of the puzzle to work with. Beyond the usual cdp/sh Mac add add/arp and the simple commands like that, I tend to wonder what « a pro would do then ». Simply, are there any good materials that could help with daily practical troubleshooting in DC lan? I find most stuff out there focuses on new concepts introduction and then moves on to the next.

Cheers