Unable To Access Certain Sites "dns_probe_finished_nxdomain"

On my laptop, I'm unable to access several popular sites, such as Twitter and even MajorGeeks!

I tried searching the error code online, but couldn't find a fix for the latest version of Windows. Also, both Chrome and Firefox were giving me error messages. Can anyone offer assistance on what to do about the following error messages? Thanks.

Chrome:
This site can’t be reached
twitter.com’s server DNS address could not be found.
DNS_PROBE_FINISHED_NXDOMAIN

Firefox:
Server not found

Firefox can’t find the server at twitter.com.

Check the address for typing errors such as ww.example.com instead of www.example.com
If you are unable to load any pages, check your computer’s network connection.
If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.

 

Download and run Tweaking.com - Windows Repair Portable.
http://www.majorgeeks.com/files/details/tweaking_com_windows_repair_portable.html

Run the software in Safe Mode with Networking.
If you are confident there are no other problems, go directly to the Repairs tab.
Ensure the following are selected: (the numbers might differ)
09 - Repair Hosts File
13 - Repair Network
15 - Repair Proxy Settings
Click Start Repairs.
Restart your PC.

 

The solution is quite simple. 99% of the times, the issue is with DNS servers.
Follow this guy guide which is easy to understand - https://www.atulhost.com/dns-probe-finished-nxdomain