In the last post we talked about how computers only understand numbers not names, in this post we’ll talk DNS. It’s how the computer knows what number goes with what name without knowing every
possible combination.

IP addresses can also change, so a computer would not only have to keep up with every possible combination but also all of the possible changes every second of every day.  Remember, there’s 4294967296 IP addresses. This translates to ‘a lot of them’. I’m not sure even a superhero could do that without help. Hrm. Maybe Batman or Iron Man could build something.

Now in the old days of the internet, this was possible. It wasn’t that big. Now… it’s that big. I mean, we’re running out of IP addresses and there’s 4294967296 of them.  Since we have no superheroes to solve this, we had to rely on the geniuses that created the whole thing to begin with. They’re the superheroes of the Internet!

Back to what DNS is. It’s a system that takes a name and returns an IP address. When you open your web browser to go to www.google.com, the first action it takes is to find that IP address using DNS. It asks the server known as a name server.   It doesn’t just ask any name server though, it asks the servers known as the roots.

The roots are a collection of name servers that only know where other name servers are.  It’s like a super search engine.  Suppose there’s a search engine that tells you if you need to go to Google or Bing or Yahoo or even Wikipedia to do your search.  You have to go to the super search engine first, then to that engine, then FINALLY to your answer.

In the case of DNS, you go first to the roots (that is, super search engine) who tells you what name servers know the answer for domains that end with com, and then that name server will tell you the name server that knows the answer for google.com.

No one name server knows all, it’s what is called a distributed system. This means if one name server is taken off line, it still works. Unlike the Death Star, that’s a single system. Blow that thing up and there goes the Empire!  Or those droids in Phantom Menace.  They blew up the one ship that controlled all the droids and WHOOPS, there goes all the droids offline!

If you want to find the IP address for www.google.com, there’s a command for that.

Alpha:~ computerlamp$ host www.google.com

Try it out, see what you get!