This is a wonderful talk about learning. I have pretty much the same process: when being confused gets to be intolerable, I go and learn something. I would just add that once you learn it you should write it down. Personally I keep man pages in ~/man/manpj, but everyone has their own system. Ideally it should be as unpolished and secret as possible, so that writing it down takes just an instant and there is no pressure to polish it. But it should still be as accurate as you can make it (or if you have further confusion try to write down yet-unanswered questions). Anyway if you spent 2 hours to figure something out, what's so bad about spending 10 minutes to write it down? You'll remember it much better, and if you do forget then you can refresh your memory.
On DNS: I remember when Julia's DNS playground showed up on HN, and one thing I didn't see explained then was my own personal 10-year (no, 20-year!) DNS confusion: iterative vs recursive lookups. In an iterative lookup, you have to keep asking one DNS server after another for answers until you get what you need. In a recursive lookup, your DNS server does that. What doesn't happen is you ask server A, then A asks server B, then B asks server C, etc. That is the model that "recursive" suggests to me, but it's wrong. It's more like your server does the iterative request that you would have done yourself. At least, that's my understanding today. I hope I got it right! :-)
You nailed it! Recursion, propagation, registry, registrar, registrant. Naming in the DNS could — ironically — use some work. But it's too late now, I suppose.
On DNS: I remember when Julia's DNS playground showed up on HN, and one thing I didn't see explained then was my own personal 10-year (no, 20-year!) DNS confusion: iterative vs recursive lookups. In an iterative lookup, you have to keep asking one DNS server after another for answers until you get what you need. In a recursive lookup, your DNS server does that. What doesn't happen is you ask server A, then A asks server B, then B asks server C, etc. That is the model that "recursive" suggests to me, but it's wrong. It's more like your server does the iterative request that you would have done yourself. At least, that's my understanding today. I hope I got it right! :-)