It's a book about UNIX system administration with Webmin. I made about $10k in the first year or so after it was published, and then I've made $100-$400 per quarter ever since. I haven't done the math on what those ongoing royalties added up to. I just consider it "mad money". I buy myself somethin' pretty with it whenever it comes in, like a Nintendo DS, a BMX bike, or something similarly goofy.
Oh, and I received a one-time payment of $3000 for the Japanese translation. I really take great satisfaction in that one...it also looks awesome on the shelf. The American version is cute, but the Japanese version is simply amazing.
It is obviously a niche book, and a more general topic would have probably sold more (the best I ever saw it ranked at Amazon was in the 3000s, I think). But, it had ancillary value to me, so I had already written about half of the content before I ever had a book deal for it. It was also free online from the very beginning, so my website was probably competing with book sales. I guess, to be fair, I've gotten probably tens of thousands of dollars worth of marketing value out of that content over the past 8 years or so (I was working on it in one form or another from 2000, or so, onward, and it has been responsible for a large portion of the organic web traffic my two businesses have received). The book (and the wiki that replaced it) has consistently received 30,000 monthly visitors, or more, for as long as I can remember...that's an awful lot of free ad impressions (we have links to our products in strategic locations within the wiki content, and I had banner ads for my previous business' products on every page in the old non-wiki version). It's really high quality traffic, and I'd pay over a buck a click for that kind of traffic from Google AdWords.
Actually, now that I'm thinking of it in those terms, it was probably a great investment of my time. I should probably write another one. But, I spent a lot of time writing it. I'd probably go faster today, for a number of reasons.
Hey, what a coincidence...me too!
http://www.amazon.com/Book-Webmin-Learned-Stop-Worrying/dp/1...
I've also been a contributor on an alternative DNS server in the distant past...back when it was fashionable to hate BIND.
Meanwhile, the reason I brought up djbdns is that it has automatic best-practice behavior for a lot of basic DNS config issues, like matching PTR records, or setting up reasonable TTLs and SOA field values. It's right there in the data format.
BIND also has reasonable defaults, and there are tools (Webmin, for example, just to throw something out there completely and utterly at random) that make it easy to get all of the "reasonable default" things you've mentioned right.
You're going to have to add this to the list of topics I'm insufferable about.
OK. But you're still wrong.