Computing Foundations from Zero
by Sergey Okinchuk
Wi-Fi, Cables, and the Physical InternetNames versus Numbers

Chapter Seven · Part 2: The Network

Finding Things: DNS

You type a name; the computer needs a number. This chapter is about the quiet translation that happens every time you open a site — turning example.com into the numeric address that the network actually routes to.

3 topics

In the last chapter the request you make when you open example.com traveled out over Wi-Fi and cables to reach another computer. But there's a gap we skipped over: you typed a name, and the network only knows how to find things by number. Something has to bridge that gap before the request can go anywhere at all.

That bridge is the subject of this chapter. Three topics build it up: why humans use names while computers use numbers, the system that translates one into the other, and how the full web address in your browser bar is put together — so that by the end, the first invisible step of opening a website stops being invisible.

Before a request can travel, the name you typed has to become a number
You type a nameexample.com
→
DNS looks it upname → number
→
It gets a numberan IP address
→
It connectsrequest can travel

Topics in This Chapter

Topic 24
Names versus Numbers
Why you type a name like example.com while the network only finds things by number — and why something has to translate between the two, automatically, every time.
Concept
Topic 25
DNS, the Internet's Phonebook
The Domain Name System — the shared directory that turns a name into its numeric address — what it looks up, what it doesn't store, and why "it's always DNS" is an engineer's joke.
Concept
Topic 26
What a URL Is
The web address in your bar isn't one blob — it's parts that each mean something: the scheme, the domain, the path, and the https at the front that means the connection is encrypted.
Concept