In this case a DNS error, which are common in networked servers. Here there is more information from which to investigate the fault. The Description often provides enough information to tell you exactly what happened, like in this case. However it can also be frustratingly cryptic, and even worse, just contain hex code.
There was a lot of negative feedback from server administrators about this, so from Server 2003 onwards a new information repository was made available directly from Microsoft.
The link at the bottom of the description window contains a link to Microsoft’s Technet resource which may have more information. This site is maintained by Microsoft but is updated with information provided by users, so often has a better description, or more information than Event Viewer alone.
There will be times when Event Viewer simply doesn’t have the information for you. This isn’t always Microsoft's fault, especially when third party applications are causing the issues. The system depends on the information it receives from each program, which is sometimes sadly lacking.
There is enough information available through Event Viewer for most people to be able to effectively monitor and troubleshoot their systems. Now you, too, know how to use Event Viewer and obtain information on how to monitor system and application performance.