Google's “Director of Engineering” Hiring Test

I'm amazed he knew things in such detail. I mean who would know just how long a MAC address is? Or what the actual SYN/ACK etc tcp flags are? You just need to know what they're used for, and if you need the specifics, you'll find out with a single search. He seemed to know that as well though. Kernighan for bit twiddling algos, that kind of thing.

It's a bit strange to have someone non-technical interviewing a techie. You end up with stupid discussions like the one about Quicksort. If you point out qs is one of several things with the same big-O, you'll probably also get it "wrong". But the real problem is that a guy who is just reading off a sheet can't give any form of nuanced feedback. Was the guy blagging the sort algo question? Did he know if in detail? Does he know what the current state of research on that area is? There's no way to know that if your guy is just a recruiter, but I'm sure even a relatively junior coder would be able to tell if someone was just doing technical word salad.

I wonder what would happen if ordinary people recruited for medical doctor jobs? Would you be comfortable rejecting a guy who'd been in medical school for 10 years based on his not knowing what the "funny bone" is? Wouldn't you tell your boss that you felt a bit out of that league? It's amazing you can get someone to do this without them going red in the face.

People that have been around know such things. At one point, Richard Stevens (RIP) was god. Every programmer had a copy of TCP/IP illustrated, Advanced Unix Programming and Unix Network Programming. If you wanted to do anything network, you had to write your own servers, you had to understand the details. The breath of knowledge was wide and the depth was just as deep. Ask around on HN, and you will probably be shocked how many that know such things. :-)

And then, the world developed robust, well-maintained, open source libraries that do all of that for you. Now, in 99% of commercial software engineering, you don't actually need to know any of those details, in the same sense that you no longer need to know exactly how many transistors and diodes are used to build the adder on the CPU. It simply no longer matters in almost all cases. Your time is much better spent moving on to higher level problems.

If you're interviewing for the rare 1% case where the job will actually require you to tinker with a TCP stack, then by all means ask about those details. For 99% of programming jobs today, it's irrelevant trivia used as nothing more than an ego measuring device.

None of that matters, until it does :).

I feel like I've seen 2-3 articles alone in the last month that has rediscovered head-of-line blocking and UDP. I'd say 1/10 engineers I talk to even know what cache aware datastructures are.

The thing that separates someone who can just string together whatever they find on npm to people who build real systems is this deep understanding. You're not going to need this for your standard LoB apps. However if you're in the business of building software you're definitely going to want people like this.