Before you change your DNS settings to use Google Public DNS, be sure to write down the current server addresses or settings on a piece of paper. It is very important that you keep these numbers for backup purposes, in case you need to revert to them at any time.
Follow the below steps to set the Google Public DNS.
1) On your keyboard, press the Windows logo key and R at the same time. Type control panel in the empty box and click OK.
2) Select View by Small icons then click Network and Sharing Center.
3) Click on Change adapter settings.
4) Right-click on Local Area Connection or Wireless Network Connection, then click Properties.
5) Click on Internet Protocol Version 4 (TCP/IPv4) then click Properties.
6) In General tab, do one of the following, depending on whether ‘Obtain DNS server address automatically’ is already selected. Either:
a) If Obtain DNS server address automatically is not already selected, select it, then click OK:
b) If ‘Obtain DNS servers address automatically’ is already selected, select ‘Use the following DNS server address’ instead, then enter the following server address and click OK:
Preferred DNS server: 220.127.116.11
Alternate DNS server: 18.104.22.168