How to make Java honor the DNS Caching Timeout?

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Per Byron’s answer, you can’t set networkaddress.cache.ttl or networkaddress.cache.negative.ttl as System Properties by using the -D flag or calling System.setProperty because these are not System properties – they are Security properties.

If you want to use a System property to trigger this behavior (so you can use the -D flag or call System.setProperty), you will want to set the following System property:

-Dsun.net.inetaddr.ttl=0

This system property will enable the desired effect.

But be aware: if you don’t use the -D flag when starting the JVM process and elect to call this from code instead:

java.security.Security.setProperty("networkaddress.cache.ttl" , "0")

This code must execute before any other code in the JVM attempts to perform networking operations.

This is important because, for example, if you called Security.setProperty in a .war file and deployed that .war to Tomcat, this wouldn’t work: Tomcat uses the Java networking stack to initialize itself much earlier than your .war’s code is executed. Because of this ‘race condition’, it is usually more convenient to use the -D flag when starting the JVM process.

If you don’t use -Dsun.net.inetaddr.ttl=0 or call Security.setProperty, you will need to edit $JRE_HOME/lib/security/java.security and set those security properties in that file, e.g.

networkaddress.cache.ttl = 0
networkaddress.cache.negative.ttl = 0

But pay attention to the security warnings in the comments surrounding those properties. Only do this if you are reasonably confident that you are not susceptible to DNS spoofing attacks.

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