Sun Microsystems Netscape Enterprise Server, Administrator'S Manual

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Using perfdump Statistics to Tune Your Server
246 Netscape Enterprise Server Administrator’s Guide
impact performance. When the server receives a request from a client, the
client’s IP address is included in the request. If DNS is enabled, the server must
look up the hostname for the IP address for every client making a request.
DNS causes multiple threads to be serialized when you use DNS services. If you
do not want serialization, enable asynchronous DNS. You can enable it only if
you have also enabled DNS. Enabling asynchronous DNS can improve your
system’s performance if you are using DNS.
Note
If you turn off DNS lookups on your server, host name restrictions will not
work, and hostnames will not appear in your log files. Instead, you’ll see IP
addresses.
You can also specify whether to cache the DNS entries. If you enable the DNS
cache, the server can store hostname information after receiving it. If the server
needs information about the client in the future, the information is cached and
available without further querying. You can specify the size of the DNS cache
and an expiration time for DNS cache entries. The DNS cache can contain 32 to
32768 entries; the default value is 1024 entries. Values for the time it takes for a
cache entry to expire can range from 1 second to 1 year (specified in seconds);
the default value is 1200 seconds (20 minutes).
It is recommended that you do not use DNS lookups in server processes
because they are so resource intensive. If you must include DNS lookups, be
sure to make them asynchronous. For more information on asynchronous DNS,
see the Performance Tuning page in the online help
enabled
If asynchronous DNS is disabled, the rest of this section will not be displayed.
Tuning
Add “AsyncDNS on” to
magnus.conf
.
NameLookups
The number of name lookups (DNS name to IP address) that have been done
since the server was started.
This setting is not tunable.