Do you mean to tell me that the guy who created a bubble sort algorithm on a whiteboard during his interview can't set up and manage a WordPress blog that scales reasonably well, and that I need to hire a dedicated systems administrator?

Where i work, we give prospective sysadmins the same simple programming problems as programmers. Our infrastructure is run with automation - Puppet, plus lots of juicy devopsy madness written in Ruby - so our sysadmins do need to have at least rudimentary programming ability.

If they pass that, we don't give them any more programming tests. We give them a hands-on sysadmin assault course problem, where they have to SSH into an EC2 box that has been carefully broken by our devious chief sysadmin, find out what's wrong, and fix it. They do it in a tmux session, with some kind of audio link (Skype, Hangout, etc), so one of our guys can watch and talk to them as they do it. I've listened to several people running through it, and it sounds terrifying.