The parent clearly said "so many people" and not "everyone" - that's a really important difference!
I really struggle to believe that a competent software developer would be unable to answer this question with some degree of accuracy. It's not like it's a networking question - it's fantastically open-ended and covers everything from hardware, operating systems, networking, GUIs... and that's useful flexibility. On top of that, it's useful to help judge communication skills - engineers must be able to clearly express ideas, understand the audience that they're communicating with, and be able to discuss and reason with other engineers.
I would not hire an engineer who was not able to answer this question.
He said "really had only one person answer it reasonably in all these years ". Are we going to quibble about this wording?
Let's see. I've done flight software. I've done cancer statistic software for the NIH. I've done autonomous robots and UAV. I've done drones. I've done weapons systems for the military. I've done mapping applications back on 486 machines with 16 bit software (hard to be responsive in that environment). I've design/built/debugged circuit boards. I've disassembled compilers and sent bug reports back to the manufacturer. I've done machine vision and computer vision. I've done simulation, solved partial differential equations, built bayesian filters.
But, you know, I haven't had to do anything significant with resolving google.com. I mean, I know that it resolves to something like 145.234.34.45, I know there is a difference between TCP and UDP, and a few other things, but I pretty much just need to open sockets once in a while. I'm pretty much the goto person for hard problems whereever I've worked. I've written articles, and am writing a book.
How does not knowing some specific fact make me unhirable?
"there are no good engineers". Well, I guess there is one, since one person was able to answer the question.
But, you know, I haven't had to do anything significant with resolving google.com. I mean, I know that it resolves to something like 145.234.34.45, I know there is a difference between TCP and UDP, and a few other things, but I pretty much just need to open sockets once in a while. I'm pretty much the goto person for hard problems whereever I've worked. I've written articles, and am writing a book.
You are actively answering the question here - this is exactly the sort of thought process and reasoning that would be required. There are no specific facts - that's the point. And I can help but feel you've missed that.
I could talk about this question for hours. You probably wouldn't want me building an autonomous robot or drone unless it was covered in pillows and safely contained far away from children and combustible liquids.
Does this make you unhireable? No, not if you're upfront about it - "I haven't done much networking." OK, well given your work history I'm sure I could buy you a book or two and you'd be able to pick it up with no problems. That said, if the job was for a network engineer, you might not be at the top of the list. Or maybe you would be, who knows? I think a GOOD interviewer wouldn't pass you over because of one question.
Am I unhireable as a drone engineer because I'd have to look up some basics of computer vision, control systems or other domain-specific stuff? No, probably not - I've done very well in a lot of different technical roles and I have a strong background in mathematics. That said, if you and I were up for the same job, I wouldn't be holding my breath for an offer letter.
Nobody can know everything about anything. Smart interviewers understand that. People who don't aren't people you want to work with anyways.
You're not unhirable, but if you applied for a senior web systems/operations position on my team, you probably wouldn't be hired. It's not because you're not a smart guy, but you don't have the experience we're looking for. Seems pretty easy to understand.
Also, if your resume says you're a web systems person or something like that, and you can't actually explain some details about DNS is doing, I have to wonder about the mismatch...
Context is important. My team is a web systems team. I wouldn't expect someone that has written flight software to know the answers. I would expect someone that is advertising themselves as a senior web developer or web systems guy to.
It's not about the specific answers - it's about being able to reasonably construct a model about how a system might work, based on the knowledge you do have, and clearly communicate that model (including its limitations!) to another engineer.
Sure, if you are a dedicated embedded device programmer who has never used a web browser or engaged in networking of any kind, then maybe you like unaccountably not be able to construct a compelling description of the process. But I find that unlikely; all I can suggest is that if you are hiring for such a position, then a similar question more tilted towards a particular field would be equally useful.
The overall idea of an open-ended question like this is sound.
My usual "Pass" answers end up being something specific to the stack a good .net developer should know, with a mutual agreement of just how awesome it is to think about the smallest steps and finding out how deep - even if in hobby terms - that person's drive to understand it is. There's no rattling off a "freebie" answer to it.
I really struggle to believe that a competent software developer would be unable to answer this question with some degree of accuracy. It's not like it's a networking question - it's fantastically open-ended and covers everything from hardware, operating systems, networking, GUIs... and that's useful flexibility. On top of that, it's useful to help judge communication skills - engineers must be able to clearly express ideas, understand the audience that they're communicating with, and be able to discuss and reason with other engineers.
I would not hire an engineer who was not able to answer this question.