When a Windows 2000 DNS server responds to DNS queries, it doesn't respond with the first corresponding record. Instead, it responds with records in turn, cycling through the matching records in what's referred to as round robin DNS.
The result of round robin DNS is that one client receives the first host record, the next receives the second, and so on. In effect, round robin DNS points clients to different host IP addresses for the same host name.
Round robin DNS provides a simple mechanism for load balancing between servers that supply the same resource, such as a Web site. For example, if your existing Web server begins to experience a relatively high workload, you might consider putting in another server, duplicating the content, and load-balancing the requests for the site across the two servers. Using round robin DNS to load-balance the traffic is one very quick solution for equalizing server load.
However, in some situations, you might not want to load-balance queries in this way. For example, you might prefer to use a primary server as long as it's available, only using secondary servers when a primary server drops offline.
If this is the case, you can disable round robin DNS, and the DNS service will return the list of hosts in the same order as they exist in the zone. Keep in mind that you can only enable or disable round robin on a per-server basis; you can't control round robin at the zone level.
To disable round robin DNS in Windows 2000 Server, follow these steps:
- Open the DNS console.
- Right-click the appropriate server, and choose Properties.
- On the Advanced tab, deselect the Enable Round Robin check box, and click OK.
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