[jmccree]

I can't second this enough. I've held the job title "DevOps Engineer" twice, and the #1 thing is having enough of a background of all areas to pickup any part of the stack and run with it.

If you want to hire devops, the best interview question I've ever heard is (I believe) from John Allspaw. It's simply "describe what happens from when you enter an address and click go in your browser til the page is displayed".

The beauty of this question is, it's not a trick, there's no right or wrong, but it shows how narrow or wide a scope the person has. Do they mention the browser, os, resolver DNS caches? Do they focus on TCP or HTTP? Do they describe how BGP routing works and the carrier hotels the connections go through? Do they mention how they're may be proxies, load balancers, etc before getting to the web servers? Do they understand how the request is transferred to your programming language of choice? Do they know how css/js assets are loaded by the browser and benefit of using multiple subdomains? Do they walk you through how the browser does the rendering?

I've asked that question to every candidate I've interviewed since I've heard of it, and it's never failed to enlighten me of where the candidate's strengths lay.

From just my questions above, you can likely tell I have little interest in the OS/hardware layer. Somebody else may emphasize all the kernel caches and I/O operations, etc. :)