Curious what type of roles you interview for, are they networking-centric? Iirc this is CCNA-level material, I'd expect anyone working in networking to be able to describe how traceroute works. I've used it more as a smoke test question than a question that most people don't know.
Even seasoned network engineers get it wrong.
Traceroute is simple. Sure, there's lots you can do to enrich the data you receive (e.g, reverse DNS and geolocation), or sending multiple sequences to identify equal cost multipath. But these are not inherent or necessary to perform a traceroute.
And understanding why different protocols exhibit different behavior / observe different metrics, or why some nodes don't send ICMP TTL expired, is important. But that's more in line with what you call "using it to troubleshoot", which is not "how it works."
But "how traceroute works" is simple: First you send a packet with TTL=1, then you send a packet with TTL=2, and so on. That's it, that's how it works.
Some candidates throw up their hands immediately, which makes it a short interview. Some candidates already know, which makes it a useless question and we move on to other things. For everyone else, I think it's a good interview question.
Have you never been asked a question in an interview that starts a discussion or has follow up questions? In isolation its not a good question, true for most questions, but to initiate something deeper its good. After the initial explanation of how it works you can get into how you have used it, what kind of issues you have solved with it. Then maybe look at an actual case and give your interpretation of the data. You could get into router hardware architectures, what the control/data planes are, why some drops in the output are not a problem and when they are, ECMP, why bidirectional traceroutes are useful, routing topology, flapping routes, etc.
Here's a link to their videos: https://www.youtube.com/playlist?list=PLO8DR5ZGla8iVN2v3UKkR...
This is the ras' "Troubleshooting with Traceroute" tutorial: https://www.youtube.com/watch?v=WL0ZTcfSvB4&list=PLO8DR5ZGla...
Slides: https://archive.nanog.org/meetings/nanog47/presentations/Sun...
(There are one or two other traceroute tutorials, not sure how different they are from the above, e.g. https://www.youtube.com/watch?v=4dUqVlZ6trU&list=PLO8DR5ZGla... ).
We use the Internet every day. I like folks to have an idea how it works, to be intellectually curious, and to be generally informed about the technology they use.
The traceroute man page explains how it works.
FWIW, my CS degree included a networking class.
...huh. I'm realizing my CS department was pretty weak. but tbf I knew how traceroute worked by high school, so it didn't matter.
