A good source of information in troubleshooting any server issue are the event logs. Lync Server 2010 creates a dedicated event log for informational activities, warnings, and errors within the standard Windows Server Event Viewer console. To view this event log, use the following steps:
1. Click Start.
2. Type eventvwr.msc and click OK to open the Event Viewer Microsoft Management Console.
3. Expand the Applications and Services Logs folder.
4. Click the Lync Server log.
5. Examine the log for warning or error events, which might provide additional insight into any issues.