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.

> I mean who would know just how long a MAC address is?

Uh, my main languages are PHP and Python (high level stuff) and I'm a student (not someone with 10 years of experience) but I knew that. 3 bytes for the vendor block, 3 bytes for the device.

> Or what the actual SYN/ACK etc tcp flags are?

Yeah the actual bytes, who ever uses that? A MAC address I've seen plenty of times in my life as hex, and I've seen the TCP setup flags being exchanged plenty of times in Wireshark and looked up the hex once when I was implementing TCP from scratch, but I still wouldn't expect anyone to know that.

> You just need to know what they're used for

Agreed on that. I wouldn't blame anyone for not knowing the size of a MAC address, I just didn't think that one is that obscure.

> I'm a student (not someone with 10 years of experience) but I knew that. 3 bytes for the vendor block, 3 bytes for the device.

That is why you know the answer. Come back in 10 years and let us know if you still know it. What you think might be mainstream in a computer science class are rarely used in application. And if they are they can be easily looked up.

I used to know the exact effective distance of a CATV cable when I was a student. Useful? Sure. Something I need to remember for the rest of my life? Definitely not.

As another example, in 17+ years writing ISO level 7 programs, I have never once needed to use the Mac address.