My brother and I came up with an interview process for help desk positions many years ago. It was sort of an open-book exam. He set up a computer and a network printer. I believe he purposely misconfigured something with the networking of the network printer, possibly one other issue too.

They had 1 hour, utilizing any resource on the internet they wanted, to correctly configure the network printer. If they completed it, great, if not, he'd go through and see what their troubleshooting process was, what they researched, etc.

This type of interview worked really well for hiring help desk staff, but obviously hiring a software engineer and evaluating them is much more difficult.