Troubleshooting the Central License Service

For common errors associated with the central license service, please see the following Knowledge Base articles:

Running ArcGIS, if I recieve the error message "Cannot find SERVER hostname in network database", what should I do?

Running ArcGIS, if I receive the error message "Checkout exceeds MAX specified in options file", what should I do?

Using ArcGIS, why am I getting the error message "User/host not on Include list for feature"?

When installing ArcGIS, how do I correct the error "Hostname entered in invalid"?

Using ERDAS IMAGINE, how do I correct the error message "Cannot find valid license information needed for IMAGINE Essentials"?