You have to think of and understand the Internet’s Domain Name Service -DNS- as a System.
The DNS is the system which, in its primary function, converts Internet domain names that you type into URL bars, or hyperlinks that you click on a web page into numeric IPv4 and/or IPv6 addresses. In a sense, the DNS system is the phone book of the Internet (for those who don’t know, a phone book was a list of numbers and names). You can imagine this database looks something like this:
| IP Address | URL/Name |
| 165.227.86.21 | cellstream.com |
| 2604:a880:400:d0::850:9001 | cellstream.com |
| 138.197.71.240 | netscionline.com |
| 2604:a880:800:a1::7e4:8001 | netscionline.com |
To understand how this works, let’s start with your computer – we will call it the client. You type in some URL into your web browser and hit <Enter>. Here is an example:
Your computer needs to translate the Fully Qualified Domain Name part into an IP address.
The first thing your system does is it looks at its local DNS Resolver Cache. If you have visited that same site in the last 24 hours, it will be there, and job done, we can set up a TCP connection to that server and then do an HTTP GET.
To display or clear the DNS resolver cache in Windows, see the examples below:
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