"Explain to me how the internet works."
I believe it has all the characteristics of a good interview question.
It’s an open question#
There’s no right or wrong. The candidate can tell whatever he/she wants, it’s about how they explain it and how comfortable they feel doing so. It will inevitably be followed by the question “could you be more specific?” to get a feel of where you’re going with the question.
Don’t answer. Let them figure it out as they try to explain.
It’s for network engineers#
For network positions it’s a great way to talk about routing, IP, VLANs, BGP, networks, OSPF, AS-numbers, …
It’s a perfect entry to discuss anything deeply technical afterwards. If during the answer they show a thorough understanding of one the layers, dive in. Find out what they’re passionate about, because at the end of the day, it’s that passion that drives us .
It’s for sysadmins#
As a sysadmin you can explain how servers work, the application layers, web- and database servers, caching, DNS, TCP/IP, …
This is a good time to show how you fully understand the server stack from top to bottom. This could even be a good time to inject a personal hero-story of an epic debug mission that succeeded for you, by analysing the server stack entirely.
It’s for webdevelopers & marketeers#
Understanding the basics of “the internet” is crucial for anyone involved in the web. Therefore being able to explain, from a high-level, how it works puts the candidate in a better position in general.
If something ever goes wrong, you’ll know you have a candidate that not only knows its own field, but has enough knowledge to think outside the box and look at the bigger picture to troubleshoot and diagnose the problem.