Compare what you know with what you don’t know

SUMMARY: Ed Wilson talks about using comparison in writing

edWilsonPic_HeadAndShoulders_2_InchOk, so one day my wife and I were on a plane to Hawaii. Our seats were not side by side, in fact, she was across the plane. I was busy working on a book on Tcp/Ip. My goal was to complete the book by the time we landed in Hawaii, and when we got to the Hotel, I was going to send it off to the editor. Therefore, I was head down on my project.

Sitting beside me was an elderly man. He was a talker.

“What are you doing over there sonny?”

I hate being called sonny. “I am working on a book. My deadline is tonight, and so I must finish this last chapter before we land in Hawaii so I can send it to the editor,” I said. I hoped the additional information about an impending deadline would deter the chattiness in him. I was wrong.

“So, what is the chapter about?”

I decided to be obscure, and figured that he would realize he was out of his depth in dealing with an ubergeek. “It is about DNS.”

The old man seemed to be determined, “So what is DNS?”

Oh good grief, “DNS is essentially a database. It contains a mapping between IP addresses and host names that are used on the Internet. The letters stand for Domain Naming System.” Now that will shut him up for sure, I thought.

“So what is is good for? Why do we even have it,” he asked.

I gave up. I was not going to shut this annoying old man up until I explained DNS to him. Let me think. How can I explain a low level internet protocol to an eighty year old man who looks and sounds like he has never seen a computer in his life. Ah … I got it.

“So have you ever walked into a large office building in downtown?”

“Yeah, those places are real swank.”

“What did you notice about them?”

“Hmm, lets see. Well usually, they have marble floors, a fountain somewhere, and there is always a reception desk off to the side.”

“And what is the reception desk for?”

“Well, I suppose that if I do not know the address of where I am going, I can go up to the receptionist and ask for the office number of Mr. Jones, assuming that I am going to see Mr. Jones.”

“Right. Now what if the office building was really small, I mean like it was really a converted house and only a bedroom or two was converted into offices. And there was no receptionist. What would you do then?”

“I guess I call out and say Mr. Jones?”

“Exactly. Now why don’t they call out in the large office building and save the cost of the receptionist?”

“Because it would be so noisy, that no one would be able to hear themselves. In fact, they would miss the call outs from all the other people visiting the building.”

“You are absolutely correct. So when computers call out, it is called a broadcast. It works for small networks that are only on one floor, or subnet. For larger networks with many different floors, or subnets, you need a central directory – the receptionist. The receptionist is the DNS database. You query her, or ask her to resolve a name to an address. And that is what DNS does.”

“Well that is very nice young man. Thank you.”

“No, thank you. Your questions helped me frame the introduction to my chapter on DNS, I was struggling with how to introduce the topic, and you have given me the perfect way to describe it. Now, I really need to get this written down before I forget it.”

And with that, he pulled out a magazine, leaned back, and went to sleep. If only he had been around for the 20 other chapters, it might have been a better book.

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