The number of current cache entries and the maximum number of cache entries. A single cache entry represents a single IP address or DNS name lookup. The cache should be as large as the maximum number of clients that will access your web site concurrently. Note that setting the cache size too high will waste memory and degrade performance.
You can set the maximum size of the DNS cache by:
Adding the following line to the magnus.conf file:
Init fn=dns-cache-init cache-size=1024
The default cache size is 1024
Entering or changing the value in the Size of DNS cache field of the Performance Tuning page in the Server Manager