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What's DNS?

Gabriel Guzman on April 25, 2018

DNS is basically the address book of the internet. When you type www.duckduckgo.com into your browser, the computer needs to figure out how to get...

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Eugene Vedensky • Sep 24 '19

Hey this is kind of awesome thanks for writing this. Question about CNAME: is the CNAME yet another shortcut to the ip? In other words, if I type in the CNAME into the browser, what's the process of resolving to one of those IPs look like. Does is resemble something like this data structure?

{
      'duckduckgo.com': {
        'www.duckduckgo.com': [
          '23.21.193.169',
          '107.20.240.232',
          '184.72.104.138'
        ]
      }
    }

Gabriel Guzman • Sep 26 '19

Hi Eugene, exactly. A CNAME is basically a shortcut or an alias to an A record. A CNAME can't point directly to an IP address, it always points to another name.

CNAME:  myhost.duckduckgo.com -> A: www.duckduckgo.com
CNAME:  duckduckgo.com -> A: www.duckduckgo.com 
A: www.duckduckgo.com -> IP: 23.21.193.169', '107.20.240.232', '184.72.104.138

So, you can have any number of CNAMEs that point to any of your A records (or names) but not directly to an IP. A records point a name to an IP.

David Adam • Feb 12 '21

Thanks a lot. Could you please explain the last line of the article "this won't always work because you can have multiple websites running on the same server at the same IP address". If you can please explain this I would be very grateful to you.

Gabriel Guzman • Jun 18 '21

Sure, I can have multiple CNAMES pointing to the same IP address, for example:

mysite.com -> 192.168.1.30
othersite.com -> 192.168.1.30
thirdsite.org -> 192.168.1.30

When I type 192.168.1.30 into my browser, the server won't know which website I'm asking for, so it will return either the default website for that server, or an error.