The Domain Name System

A domain name server is a special type of server that connects domain 0:00 names with IP addresses, and it's a good thing we have them. 0:04 Thanks to DNS, 0:08 you don't have to keep your own address book of IPs to your favorite websites. 0:09 Instead, you just connect through DNS, 0:14 which manages a massive database that maps domain names to IP addresses. 0:18 You can always bypass DNS by typing an IP directly in your browser, 0:23 which you saw in the last video. 0:27 But could you imagine doing that every time? 0:29 And what if your favorite website gets a new IP address? 0:32 As you can probably already see, DNS is a really important part of the web. 0:35 Let's see how it works. 0:40 When it comes to DNS, proximity matters. 0:42 Depending on where you are and when you log onto the Internet, 0:45 you may use a different DNS to find websites. 0:49 [SOUND]. Meaning the DNS that looks up 0:52 teamtreehouse.com when you're at home, may not be the same DNS at work or school. 0:55 Say, for example, you hit up your local library for some free WiFi. 1:02 When you log onto the Internet, 1:07 the library's internet service provider tells your computer 1:08 what DNS to start with when looking up IP addresses for domain names on the web. 1:12 Although, not every DNS server knows every domain name. 1:18 For example, when I type in teamtreehouse.com into my address bar, 1:23 the DNS system begins by looking at the top level domain or 1:27 .com in the case of teamtreehouse.com. 1:32 It will then ask which server the domain teamtreehouse is on, 1:35 if it doesn't already know. 1:39 Within DNS there's a hierarchy of servers, so if one doesn't know, it sends a request 1:41 to the next server, and the next, until the correct website is located. 1:47 If all goes well, the server sends a short message back to the client, 1:52 your computer, saying that everything is okay, followed by the web page itself. 1:56 The DNS system is quite complex, but 2:01 the important takeaway is that DNS is the address book for the Internet, 2:03 and it's what connects domain names with IP addresses. 2:07 If you're interested in learning more about DNS, check out the teacher's notes. 2:11