DNS caching ability of the SDK
 Technote (troubleshooting)
 
Problem(Abstract)
In a networked environment, traffic to the DNS can be a problem. The SDK that ships with IBM® WebSphere® Application Server provides a DNS caching service to help reduce this traffic.
 
Cause
The caching function allows an IP address to be stored in a cache. The IP address is obtained from this cache rather than sending a request to the DNS server.
 
Resolving the problem
The SDK provides the following properties to control network address caching:

networkaddress.cache.ttl (default: -1)

Specified in java.security to indicate the caching policy for successful name look-ups from the name service. The value is specified as an integer to indicate the number of seconds to cache the successful look-up.

A value of -1 indicates cache forever.

networkaddress.cache.negative.tll (default 10)

Specified in java.security to indicate the caching policy for unsuccessful name look-ups from the name service. The value is specified as an integer to indicate the number of seconds to cache the failure for unsuccessful look-ups.

A value of 0 indicates never cache. A value of -1 indicates cache forever.

You can also specify these as generic JVM arguments:

sun.net.inetaddr.ttl

This corresponds to the networkaddress.cache.ttl, which has the same meaning and takes the same values, but can be used as a command-line option.

sun.net.inetaddr.negative.ttl

This corresponds to networkaddress.cache.negative.ttl, which has the same meaning and takes the same values, but can be used as a command-line option.

Currently there are no recommended guidelines on setting these parameters. When you select values, consider the following things:
  • Reliability of the DNS server
  • Impact of DNS traffic on the network
  • Lease time interval for dynamic IP addresses
  • DNS time to live value
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Java SDK
Operating system(s): Windows
Software version: 6.1
Software edition:
Reference #: 1207534
IBM Group: Software Group
Modified date: Jun 8, 2005