In simple words, DNS means when you type an url on your browser which will translate or convert Host names and Internet Domain into IP address.

How to Setup Google Public DNS:

1.Open Control Panel > Network and Internet > Network and Sharing Control > Change adapter settings

a) If you're using LAN connection right click on Ethernet Connection and select Properties

b) If you're using wireless connection right click on Wireless Network or Wireless Terminal and choose properties.

Now simply click on Internet Protocol (TCP/IPv4) or Internet Protocol (TCP/IPv6), and select Properties.

Now you have to enter Preffered DNS server and Alternative DNS server

NOTE : You can enter DNS server for either (TCP/ IPv4) or for (TCP/IPv6), or you can add DNS server for both.

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*Google Public DNS server for Internet Protocol (TCP/IPv4)

Preffered DNS server : 8.8.8.8

Alternative DNS server : 8.8.4.4

*Google Public DNS server for (TCP/IPv6)

Preffered DNS server:
2001:4860:4860::8888

Alternative DNS server :
2001:4860:4860::8844

After adding DNS server click on OK button.

To take changes, you need to restart your system, That's it..