code: public long getReveseDNSCacheLifetime()
              throws NumberFormatException {
  
          long value = 60*60*1000;
  
          String property = getProperty(REVERSE_DNS_CACHE_LIFETIME);
          if (property != null && property.length() > 0) {
              long parsedValue = Long.parseLong(property);
              if (parsedValue > 0) {
                  value = parsedValue;
              }
          }
  
          // System property takes precedence
          property = System.getProperty(REVERSE_DNS_CACHE_LIFETIME);
          if (property != null && property.length() > 0) {
              long parsedValue = Long.parseLong(property);
              if (parsedValue > 0) {
                  value = parsedValue;
              }
          }
  
          return value;
      }
docs: Returns the reverse DNS cache time.
  
  Defaults to 1h.
  
  @throws NumberFormatException if the cache lifetime property
  could not be parsed
  @return the reverse DNS cache lifetime in milliseconds