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Collect IIS logs with the Log Analytics agent

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Internet Information Services (IIS) stores user activity in log files that can be collected by the Log Analytics agent and stored in Azure Monitor Logs.

Diagram that shows IIS logs.

Important

This article covers collecting IIS logs with the Log Analytics agent, which is deprecated as of August 31, 2024. If you use the Log Analytics agent to ingest data to Azure Monitor, migrate now to Azure Monitor agent. See Collect text logs with Azure Monitor Agent (preview) for details on collecting IIS logs with Azure Monitor Agent.

Configure IIS logs

Azure Monitor collects entries from log files created by IIS, so you must configure IIS for logging.

Azure Monitor only supports IIS log files stored in W3C format and doesn't support custom fields or IIS Advanced Logging. It doesn't collect logs in NCSA or IIS native format.

Configure IIS logs in Azure Monitor from the Agent configuration menu for the Log Analytics agent. No configuration is required other than selecting Collect W3C format IIS log files.

Data collection

Azure Monitor collects IIS log entries from each agent each time the log timestamp changes. The log is read every 5 minutes. If for any reason IIS doesn't update the timestamp before the rollover time when a new file is created, entries will be collected following creation of the new file.

The frequency of new file creation is controlled by the Log File Rollover Schedule setting for the IIS site. The setting is once a day by default. If the setting is Hourly, Azure Monitor collects the log each hour. If the setting is Daily, Azure Monitor collects the log every 24 hours.

Important

We recommend that you set Log File Rollover Schedule to Hourly. If it's set to Daily, you might experience spikes in your data because it will be collected only once per day.

IIS log record properties

IIS log records have a type of W3CIISLog and have the properties shown in the following table:

Property Description
Computer Name of the computer that the event was collected from.
cIP IP address of the client.
csMethod Method of the request, such as GET or POST.
csReferer Site that the user followed a link from to the current site.
csUserAgent Browser type of the client.
csUserName Name of the authenticated user that accessed the server. Anonymous users are indicated by a hyphen.
csUriStem Target of the request, such as a webpage.
csUriQuery Query, if any, that the client was trying to perform.
ManagementGroupName Name of the management group for Operations Manager agents. For other agents, this name is AOI-<workspace ID>.
RemoteIPCountry Country/region of the IP address of the client.
RemoteIPLatitude Latitude of the client IP address.
RemoteIPLongitude Longitude of the client IP address.
scStatus HTTP status code.
scSubStatus Substatus error code.
scWin32Status Windows status code.
sIP IP address of the web server.
SourceSystem OpsMgr.
sPort Port on the server the client connected to.
sSiteName Name of the IIS site.
TimeGenerated Date and time the entry was logged.
TimeTaken Length of time to process the request in milliseconds.
csHost Host name.
csBytes Number of bytes that the server received.

Log queries with IIS logs

Different examples of log queries that retrieve IIS log records are shown in the following table:

Query Description
W3CIISLog All IIS log records.
W3CIISLog | where scStatus==500 All IIS log records with a return status of 500.
W3CIISLog | summarize count() by cIP Count of IIS log entries by client IP address.
W3CIISLog | where csHost=="www.contoso.com" | summarize count() by csUriStem Count of IIS log entries by URL for the host www.contoso.com.
W3CIISLog | summarize sum(csBytes) by Computer | take 500000 Total bytes received by each IIS computer.

Next steps

  • Configure Azure Monitor to collect other data sources for analysis.
  • Learn about log queries to analyze the data collected from data sources and solutions.