Last week i encountered an issue where the Web Front Ends were not displaying the main Web Application.
I triple checked all the servers including that the database servers were online, and then proceeded to check if i could access the Central Admin website on the Central Admin server. I then tried to access the Central Admin website from the Web Front Ends and was not able to resolve which means its a DNS issue.
Solution:
The Central Admin server network adapter was set to automatic. Changed it back to static IP Address and performed an IISreset on the Web Front Ends and the Web Application was restored.
1 Giant Nerd 