The IInetLogInformation::GetSiteName method obtains the name of the server instance that is being logged.
virtual LPSTR STDMETHODCALLTYPE GetSiteName( IN PCHAR pszSiteName, IN PDWORD pcbSize );
Logging modules should query for this method if a server instance has set the MD_EXTLOG_SITE_NAME flag of the MD_LOGEXT_FIELD_MASK metabase identifier.
LogExtFileSiteName, MD_LOGEXT_FIELD_MASK