You have to stop at some point. Or do you go in depth into the workings of >10Gbps transceivers? the quantum mechanics of optical fibers? how to they manufacture top-notch photodiodes anyway? You can literally spend a lifetime in these depths.
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The question is a stealth customer support question. I'm not talking about interviewing for customer support, but unless you're hiring a hermit they'll be talking to other, probably non-technical people.
I guess the standard HN car analogy would be asking a car mechanic how suspension works and you want to hire the mechanic that makes the questioner happy and comfortable and feels informed, not the mechanic who says F off noob LMGTFY or gets "stuck" in a deep corner of Hookes law analysis of torsion bars vs axial springs regardless of questioners interest or simply starts making stuff up about left handed crescent wrenches and frequency grease. Also you want a reasonably fast answer, not beating around the bush for an hour without figuring out what the customer is looking for.
Its not just dealing with non-techies anyway. I could elaborate at length on ye olde FDDI 10b/8b optical code making analogies with good old AMI/B8ZS encoding on T1 circuits to maintain clock sync, but I might have to talk to a guy about 2015-era photodiode manufacture trivia or the photodiode guy might have to talk trivia with me, and its interesting to see reactions. Usually tech people get along better with tech people even if non-tech people ask the same question which is kind of interesting.
As a strategy to "win" at an interview its pretty hard to beat a table turning approach of you tell me your mental model and I'll be your tour guide as we straighten out misconceptions as you steer us down the path to whatever it is you want answered or you reach your fill of answers. Gotta be brave for this one if they inevitably take some weird side detour, and yes they will notice if you start steering away from your own weak spot.
And the complexity is growing every second. Its glorious and confounding. I want a million life times to learn it all!
I feel the learning is like living in a fractal. Just as you feel that you grasp the scale of it, you see a whole new level of complexity.
What are some good resources for learning about >10Gbps transceivers (and high-speed communication in general)? I'm not sure where to start a Wikipedia crawl.
Very little over 10G exists on any single wavelength, its all in stacking at different wavelengths. Much as your cabletv has a zillion 6MHz wide channels holding HDTV or whatever, you can run 4, 10, whatever, 10G ethernet light wavelengths on a piece of fiber at slightly different colors.
https://en.wikipedia.org/wiki/Wavelength-division_multiplexi...
https://en.wikipedia.org/wiki/Synchronous_optical_networking
https://en.wikipedia.org/wiki/100_Gigabit_Ethernet
Note the difference between latency and bandwidth... infiniband isn't really all that fast, but it is very low latency. Infiniband-FDR "fourteen data rate" is technically over your speed criteria.
https://en.wikipedia.org/wiki/InfiniBand
You start having problems with infinitely narrow pulses because glass isn't linear enough and lasers aren't monochromatic enough, and multipath etc.
I think stopping at the MAC level would be a good place, unless you're interviewing for an EE job in which case the higher layers aren't so important.