DnsCache.scala

package services

import java.security.Security

import org.slf4j.LoggerFactory

object DnsCache {

  private val logger = LoggerFactory.getLogger("DnsCache")

  /**
    * Set the dns cache settings for the jvm to stop caching names forever
    */
  def setup() {
    val nct: String = "networkaddress.cache.ttl"
    val ncnt: String = "networkaddress.cache.negative.ttl"
    
    logger.info("cache_dns pre {}: {}", nct, Security.getProperty(nct))
    logger.info("cache_dns pre {}: {}", ncnt, Security.getProperty(ncnt))

    Security.setProperty(nct, System.getProperty("sun.net.inetaddr.ttl", "10"))
    Security.setProperty(ncnt, System.getProperty("sun.net.inetaddr.negative.ttl", "3"))

    logger.info("cache_dns post {}: {}", nct, Security.getProperty(nct))
    logger.info("cache_dns post {}: {}", ncnt, Security.getProperty(ncnt))
  }
}

for java

package outland.feature.server;

import java.security.Security;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class DnsCache {

  private static final Logger logger = LoggerFactory.getLogger(DnsCache.class);

  /**
   * Set the dns cache settings for the jvm on startup to stop caching names forever
   */
  static void setup() {
    change();
  }

  private static void change() {
    try {
      String nct = "networkaddress.cache.ttl";
      String ncnt = "networkaddress.cache.negative.ttl";
      logger.info("cache_dns pre {}: {}", nct, Security.getProperty(nct));
      logger.info("cache_dns pre {}: {}", ncnt, Security.getProperty(ncnt));
      Security.setProperty(nct, "3");
      Security.setProperty(ncnt, "3");
      logger.info("cache_dns post {}: {}", nct, Security.getProperty(nct));
      logger.info("cache_dns post {}: {}", ncnt, Security.getProperty(ncnt));
    } catch (SecurityException se) {
      throw new RuntimeException(se);
    }
  }
}