Managing and Monitoring DNS

Because of the important role DNS servers play in a Windows 2000 environment, it's important to properly manage and monitor them on a regular basis to ensure adequate performance. The following section introduces you to some of the management tasks you might have to perform on a DNS server and how to monitor your DNS server using Performance's System Monitor.

Managing DNS

Most management tasks performed on a DNS server are done through the DNS management console. When you highlight your DNS server within the DNS manager and click the Action menu, you see several options that can be used to manage different aspects of DNS. Some of the available options are summarized as follows :

• Set Aging/Scavenging for all zones ” Use this option to configure refresh intervals for resource records. This allows you to refresh resource records on a set schedule, and it keeps bad records, such as invalid URLs, out of the database.

• Scavenge Stale Resource Records ” Use this option to manually scavenge stale resource records. Stale resource records can accumulate within a zone over a period of time. For example, if a computer registers its own resource record and is shut down improperly, the record might not be removed from the zone file. Scavenging stale resource records can eliminate any problems such as outdated information.

• Update Server Data Files ” Use this option to write all changes to the zone file stored within Active Directory to disk.

• Clear Cache ” Use this option to clear the contents of the name server's cache.

From the All Tasks option listed on the Action menu, you can also perform tasks such as starting, stopping, and pausing the DNS Server service.

Monitoring DNS

Finally, you should monitor your DNS servers on a regular basis. Obviously, in large enterprise environments, you should monitor DNS servers more frequently. In any case, because DNS servers play such an important role within a Windows 2000 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 2.16). Table 2.4 outlines some of the common DNS performance counters.

Figure 2.16. DNS performance counters in the Add Counters dialog box.

Table 2.4. Common DNS Performance Counters

Counter	Description
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.