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How the Web Works

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Domain Names and IP Addresses

3:56 with Joy Kesten

A domain name is a word or phrase used to help people remember web addresses, or IP addresses. In this video let's check out how domain names and IP addresses work in more detail.

In every URL is a domain name. 0:00
A domain name is a word or phrase used to help people remember web addresses, or 0:02
IP addresses. 0:07
In this video, let's check out how domain names and IP addresses work. 0:09
In each domain name, there are a few parts labeled from right to left. 0:12
Top Level Domains, or TLDs are actually what most people think of as the end, 0:16
or extension of a domain. 0:22
A few Top Level Domains you're probably familiar with are .com, 0:24
.net, .edu, and .org. 0:30
However, this list also includes country codes, such as .uk for the United Kingdom, 0:33
.jp for Japan and .us for the United States and 0:38
even brand names, organizations and vanity words like .ninja and .name. 0:43
Top Level Domain names are managed by the Internet Corporation for 0:49
Assigned Names and Numbers or ICANN and can be found at www.icann.org. 0:54
ICANN authorize domain name registrars which are the companies responsible for 1:02
registering and reassigning domain names. 1:08
When we say domain names are organized from right to left, it means each label or 1:12
section between the dots, specifies a subdomain of the section to its right. 1:17
For example, in teamtreehouse.com, .com is the Top Level Domain, 1:22
teamtreehouse is a subdomain of .com. 1:29
If you've thought about this in terms of geography, 1:32
.com would be the country you live in, like the United States of America and 1:36
teamtreehouse is the state, or province. 1:41
Any subdomains of teamtreehouse.com, 1:44
like www.teamtreehouse.com are like the towns in the state, in the country. 1:48
An important function of domain names is to provide easily recognizable, 1:55
and memorable names to the numeric IP addresses of the servers where 2:00
the websites actually live. 2:04
If I wanted to find the treehouse website, using its domain name, 2:07
I would type in teamtreehouse.com into the address bar. 2:11
If I wanted to find the treehouse website, using its IP address, 2:15
I would type in 173.247.98.20 and 2:21
hit enter, and look, it's the same website. 2:26
Nearly everything on the web uses Internet Protocol version 4, or IPv4. 2:30
IPv4 is comprised of four numbers, each between 0 and 255, separated by dots. 2:38
IPv4 has the capacity to identify about 4.3 billion unique addresses, 2:46
but with over 7 billion people already on the planet and each person having more and 2:54
more devices connected to the Internet, IPv4 is quickly running out of space. 2:59
Luckily, there's already an alternative IP version 6 that's quickly catching on. 3:05
IPv6 will support every person on Earth 3:11
having billions of devices connected to the web at once. 3:14
IPv6 is kind of like adding more numbers to phone numbers as the population grows. 3:19
Phone numbers in a country often start with just a few numbers. 3:25
But, as more people get phones, phone numbers get longer and then, an area 3:29
code is added to differentiate the same number in different geographic regions. 3:34
IPv6 is the new format for IP addresses and 3:39
gives us billions of new phone number for all of the new devices on the web. 3:43
Now that we know a bit more about domain names and 3:48
IP addresses, let's find out how they're all connected with domain name servers 3:51