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This chapter is from the book

Monitoring DNS

You should monitor your DNS servers on a regular basis. Obviously, in large enterprise environments, you will want to monitor DNS servers more frequently than for small businesses. Because DNS servers play such an important role for a Windows Server 2003 domain, it's important that solid performance is maintained.

System Monitor

The tool most often used to monitor how services are performing is the System Monitor tool, located within the Performance console. When you install DNS, several counters are added specifically for monitoring this service (see Figure 3.13).


Figure 3.13 DNS-specific counters are added to the System Monitor tool for monitoring DNS activity

The following list outlines some of the common DNS performance counters:

  • Caching Memory— Monitors the total caching memory used by the DNS server
  • Dynamic Update Received/Sec— Determines the number of dynamic update requests received by the server per second
  • Dynamic Update Requests— Counts the total number of dynamic updates received by the server
  • Recursive Queries— Monitors the total number of recursive queries received by the server
  • Total Queries Received— Calculates the total number of queries received by the server

Event Viewer

If logging is enabled, DNS-related events can be written to the DNS log. As already mentioned, logging can be enabled using the Event Logging tab from the DNS server's Properties window. By default, all DNS-related events are written to the log. You can choose to log errors only or to log both errors and warnings. By selecting the No Events option, you can disable event logging.

You can use the Event Viewer, located on the Administrative Tools menu, to view events. When the Event Viewer is open, click the DNS log. Any DNS-related events are displayed within the right pane (see Figure 3.14). To view more detailed information about an event, double-click the event within the right pane. The Properties window for the event displays information such as the date and time the event occurred, the type of event, the user and computer under which the event occurred, and an event ID. A basic description of the event is also provided.


Figure 3.14 DNS events are logged in the Event Viewer's DNS log

DNS Debug Logging

If you want to collect detailed information about how your DNS server is functioning, you can enable DNS debug logging. Once you do, DNS data will be collected and stored in the DNS.log file. Using the Debug Logging tab from the DNS server's properties window, you can choose the type of information that you want logged. For example, you can have all incoming and outgoing packets using TCP logged.

DNS debug logging is not enabled by default. Because it can be resource-intensive and affect server performance, it should only be enabled on a temporary basis.

Replication Monitor

As mentioned earlier in the chapter, zone information can be stored within Active Directory if DNS is installed on a domain controller. This also means that zone updates can be included in Active Directory replication.

Using a tool called Replication Monitor, you can monitor the status of Active Directory replication between domain controllers. If zone information is stored within Active Directory, this also enables you to monitor replication between DNS servers.

Replication Monitor is not installed by default. It can be added by browsing to the i386\Support\Tools directory on the Windows Server 2003 CD and running setup. After it is installed, it can be launched from the command prompt using the Replmon command.

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