By default, logging sync requests and responses between Outlook and SharePoint is disabled. By enabling this setting (or when Outlook logging in general is enabled), Outlook logs most sync requests and responses to a log file stored in the user's TEMP directory. One log file is created per day (up to seven total), using the naming convention: 0-wss-sync-log.HTM, 1-wss-sync-log.HTM, and so on.
Log files can help diagnose problems with Outlook and SharePoint interactions. Each log file links to one or more XML files (also in the TEMP directory) containing detailed server response and error information. The XML filename is based on the corresponding log file; you can obtain all related diagnostic files by copying all *-wss-*.* files from the TEMP directory.