If I ask you "what happens when you load a URL" and you start talking about the operating system's handling of keyboard events, I might get the impression you're hopelessly prone to bizarre and useless digressions.
If I ask you "what happens when you load a URL" and you start talking about the operating system's handling of keyboard events, I might get the impression you're hopelessly prone to bizarre and useless digressions.
If someone goes wildly off-track and starts talking about the design of the mechanical switches in the keyboard or I am specifically interested in one area vs another then you can easily tailor it "Ok cool - lets skip ahead to the network aspects" or "lets say I've found the server and downloaded the HTML - now what?" etc.
That said, I often like to let people just talk in interviews unless I am really specifically trying to drill into one area and get specific evidence of specific skills. I might jump in with a "Ah - interesting. Tell me more about DNS" or whatever, but usually I find that the good candidates will have a lot to say, and the less-good candidates either say hardly anything, bullshit, or talk a lot but are not good communicators (confusing explanations/hand-waving/etc) ... or a combination of those things :)
I wouldn't consider it useless either, unless I'm hiring an engineer for a narrow focus on something (e.g. I want someone that knows BGP), but I've never done that.
I've found that the ability to learn is fungible.
The ability answer a question effectively instead of exhaustively is important too, though, right?
Personally, I'd be more impressed by the candidate who answers this by first asking "is there a particular aspect or perspective of this task you're most interested in?", especially if they can highlight the broad aspects involved, and offer to drill down on any in particular.
1-Is a genius and has no problem getting a job, therefore doesn't have to jump through these hoops
2- Or is probably on the autism spectrum and might be hard to work with