You cannot expect these websites to be down and it happens very rarely.
The solution mentioned below is simple and it worked very well for me.
The logic is to check if it as a browser related problem.
The logic behind using Safe Mode with Networking – If the internet connection works fine in Safe Mode with Networking, then it should be the third-party services or driver which is responsible for the problem because these are the services which are blocked in Safe Mode with Networking.The major culprits to look for in third party services Sometimes the error message happens to only some websites.Security software is another major culprit responsible for DNS Server Not Responding error.Every security software tends to get corrupted over a period of time for reasons ranging from file corruption while updating files, conflicts with other software or indirect changes to security settings as a result of intentional or unintentional changes made on your PC.My expertise are in Operating Systems, mainly Windows and Computer security which comes from my experience, working as Tech Support and Trainer for Microsoft, Symantec and Mc Afee.
Loves blogging about Technical Troubleshooting, discussing latest Gadgets, Games and doing Reviews.Check if your security software is configured properly especially the Firewall settings.Safe mode is a troubleshooting mode that allows only the essential operating system files and drivers to load.This might cause the security software to block internet connection.It is possible that your security software may have got corrupted or not working properly for variety of reasons.Then I tried the diagnostic tool link that popped up in the webpage, which showed me DNS Server Not Responding Error.