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.
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 3.11).
Figure 3.11 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 MemoryMonitors the total caching memory used by the DNS server
Dynamic Update Received/SecDetermines the number of dynamic update requests received by the server per second
Dynamic Update RequestsCounts the total number of dynamic updates received by the server
Recursive QueriesMonitors the total number of recursive queries received by the server
Total Queries ReceivedCalculates the total number of queries received by the server
If logging is enabled, DNS-related events can be written to the DNS Server 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 Server entry. Any DNS-related events are displayed within the right pane (see Figure 3.12). 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 3.12 DNS events are logged in the Event Viewer's DNS log.
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.