DNS Logging and Diagnostics

Applies To: Windows Server 2012 R2

Enhanced DNS logging and diagnostics is available by default in Windows Server® 2016 Technical Preview. This feature is also available in Windows Server® 2012 R2 when you install the query logging and change auditing hotfix, available from https://support.microsoft.com/kb/2956577.

DNS logging and diagnostics

See the following sections in this topic:

• Performance considerations

  • Debug logging

  • Audit and analytic event logging

• Installing and enabling DNS diagnostic logging

  • To install DNS diagnostic logging

  • To enable DNS diagnostic logging

• Using DNS server audit and analytic events

  • Using ETW consumers

  • Audit events

  • Analytic events

Performance considerations

DNS server performance can be affected when additional logging is enabled, however the enhanced DNS logging and diagnostics feature in Windows Server 2012 R2 and Windows Server 2016 Technical Preview is designed to have a very low impact on performance. The following sections discuss DNS server performance considerations when additional logging is enabled.

Debug logging

Prior to the introduction of DNS analytic logs, DNS debug logging was an available method to monitor DNS transactions. DNS debug logging is not the same as the enhanced DNS logging and diagnostics feature discussed in this topic. Debug logging is discussed here because it is also a tool that is available for DNS logging and diagnostics. See Using server debugging logging options for more information about DNS debug logging. The DNS debug log provides extremely detailed data about all DNS information that is sent and received by the DNS server, similar to the data that can be gathered using packet capture tools such as network monitor. Debug logging can affect overall server performance and also consumes disk space, therefore it is recommended to enable debug logging only temporarily when detailed DNS transaction information is needed.

Audit and analytic event logging

Enhanced DNS logging and diagnostics in Windows Server 2012 R2 and later includes DNS Audit events and DNS Analytic events. DNS audit logs are enabled by default, and do not significantly affect DNS server performance. DNS analytical logs are not enabled by default, and typically will only affect DNS server performance at very high DNS query rates. For example, a DNS server running on modern hardware that is receiving 100,000 queries per second (QPS) can experience a performance degradation of 5% when analytic logs are enabled. There is no apparent performance impact for query rates of 50,000 QPS and lower. However, it is always advisable to monitor DNS server performance whenever additional logging is enabled.

Installing and enabling DNS diagnostic logging

Perform the following procedures to install and enable DNS diagnostic logging on Windows Server 2012 R2. To install DNS diagnostic logging, the computer must be running the DNS Server role service.

If the DNS server is running Windows Server 2016 Technical Preview or later, diagnostic logging is already installed and you can skip the first procedure, performing only the steps in To enable DNS diagnostic logging below.

Membership in the Administrators group, or equivalent, is the minimum required to complete these procedures. Review details about using the appropriate accounts and group memberships at Local and Domain Default Groups (https://go.microsoft.com/fwlink/?LinkId=83477).

To install DNS diagnostic logging

1. If the DNS server is running Windows Server 2012 R2, download the hotfix from https://support.microsoft.com/kb/2956577.

2. Double-click the self-extracting file, for example 475151_intl_x64_zip.exe.

3. In the Microsoft Self-Extractor dialog box, click Continue.

4. Type a location where you want to save the extracted files, for example C:\hotfix. If the directory does not yet exist, you will be asked if you wish to create it. Click Yes and confirm that All files were successfully unzipped is displayed, then click Ok.

5. In the location where files were unzipped, double-click the Windows Update file, for example Windows8.1-KB2956577-v2-x64.msu.

6. The Windows Update Standalone Installer will verify that the computer meets requirements to install the update. These requirements include some prerequisite updates. When verification is complete, click Yes when asked if you wish to install the Hotfix for Windows (KB2956577).

7. If recently downloaded updates have not yet been installed, you might need to restart the computer before the current hotfix can be installed. If this is required, you must restart the computer first and then run the Windows8.1-KB2956577-v2-x64.msu a second time after the computer has completed installing necessary updates. The Windows Update Standalone Installer will notify you that installation of the hotfix is not yet complete. If this happens, and you are prompted to restart the computer, click Restart Now.

8. If the computer is ready to install the update when you run the hotfix, installation will complete and you must restart the computer for the update to take effect. If Installation complete is displayed, click Restart Now for the update to take effect.

You can confirm that the hotfix was successfully installed by viewing installed updates in the Programs and Features control panel. If the update is successfully installed, Hotfix for Microsoft Windows (KB2956577) will be displayed. You can also verify installation of the hotfix by typing wmic qfe | find "KB2956577" at an elevated command prompt. The URL and date of installation for the hotfix will be displayed if it was successfully installed.

To enable DNS diagnostic logging

1. Type eventvwr.msc at an elevated command prompt and press ENTER to open Event Viewer.

2. In Event Viewer, navigate to Applications and Services Logs\Microsoft\Windows\DNS-Server.

3. Right-click DNS-Server, point to View, and then click Show Analytic and Debug Logs. The Analytical log will be displayed.

4. Right-click Analytical and then click Properties.

5. Under When maximum event log size is reached, choose Do not overwrite events (Clear logs manually), select the Enable logging checkbox, and click OK when you are asked if you want to enable this log. See the following example.

   

6. Click OK again to enable the DNS Server Analytic event log.

By default, analytic logs are written to the file: %SystemRoot%\System32\Winevt\Logs\Microsoft-Windows-DNSServer%4Analytical.etl.

See the following sections for details about events that are displayed in the DNS server audit and analytic event logs.

Using DNS server audit and analytic events

DNS logs are compatible with Event Tracing for Windows (ETW) consumer applications such as logman, tracelog, and message analyzer. For more information about using event tracing, see About Event Tracing.

• Using ETW consumers

• Audit events

• Analytic events

Using ETW consumers

You can use ETW consumers such as tracelog.exe with DNS server audit and analytic events by specifying a GUID of {EB79061A-A566-4698-9119-3ED2807060E7}.

You can get tracelog.exe by downloading and installing the Windows Driver Kit (WDK). Tracelog.exe is included when you install the WDK, Visual Studio, and the Windows SDK for desktop apps. For information about downloading the kits, see Windows Hardware Downloads. For example, when you download and install Windows Driver Kit (WDK) 8 and accept the default installation path, tracelog.exe is available at C:\Program Files (x86)\Windows Kits\8.0\Tools\x64\tracelog.exe.

For more information about using tracelog.exe, see Tracelog Command Syntax. The following examples demonstrate how to use tracelog.exe with DNS audit and analytic event logs:

The following command will enable both analytical and audit logging:

tracelog.exe -start Dns -guid #{EB79061A-A566-4698-9119-3ED2807060E7} -level 5 -matchanykw 0xFFFFFFFF -f C:\analytic_audit.etl

While the trace is active, all analytical and audit events will be recorded in the C:\analytic_audit.etl file that was specified on the command line. You can stop tracing by issuing a stop command:

tracelog –stop Dns

After stopping the trace, you can view the .etl file in Event Viewer by clicking Action and then clicking Open Saved Log. See the following example.

The following example enables just the analytical channel and matches only the keywords to 0x7FFFF:

tracelog.exe -start Dns -guid #{EB79061A-A566-4698-9119-3ED2807060E7} -level 5 -matchanykw 0x7FFFF -f C:\analytic.etl

A logging level of 5 is used in the previous examples. The following logging levels are available:

Audit events

DNS server audit events enable change tracking on the DNS server. An audit event is logged each time server, zone, or resource record settings are changed. This includes operational events such as dynamic updates, zone transfers, and DNSSEC zone signing and unsigning. The following table summarizes DNS server audit events.

Table 1: DNS Server Audit Events

Analytic events

DNS server analytic events enable activity tracking on the DNS server. An analytic event is logged each time the server sends or receives DNS information. The following table summarizes DNS server analytic events.

Table 2: DNS Server Analytic Events