DNS on Windows Server 2003, 3rd Edition

Capacity Planning

If you have heavily populated< networks or users who do a lot of name server-intensive work, you may find you need more name servers than we’ve recommended to handle the load. Likewise, our recommendations may be fine for a little while, but as people add hosts to your networks or install new name server-intensive programs, you may find your name servers bogged down by queries.

Just which tasks are “name server-intensive”? Surfing the Web can be, as can sending electronic mail, especially to large mailing lists. Programs that make lots of remote procedure calls to different hosts can also be name server-intensive. Even running certain graphical user environments can tax your name server. The astute (and precocious) among you may be asking, “But how do I know when my name servers are overloaded? What do I look for?” An excellent question!

Memory utilization is probably the most important aspect of a name server’s operation to monitor. dns.exe, the name server process, can get very large on a name server that is authoritative for many zones. If dns.exe’s size, plus the size of the other processes you run, exceeds the size of your host’s real memory, your host may swap furiously (“thrash”) and not get anything done. Another criterion you can use to measure the load on your name server is the load the name server process places on the host’s CPU. Correctly configured name servers don’t use much CPU time, so high CPU usage is often symptomatic of a configuration ...