code: public void setDnsTtlSuccessfulQueries(int ttl) {
  		if (dnsTtlSuccessfulQueries == ttl) {
  			return;
  		}
  
  		dnsTtlSuccessfulQueries = ttl;
  		getConfig().setProperty(DNS_TTL_SUCCESSFUL_QUERIES_KEY, ttl);
  	}
docs: Sets the TTL (in seconds) of successful DNS queries.
  <p>
  Some values have special meaning:
  <ul>
  <li>Negative number, cache forever;</li>
  <li>Zero, disables caching;</li>
  <li>Positive number, the number of seconds the successful DNS queries will be cached.</li>
  </ul>
  
  @param ttl the TTL in seconds
  @since 2.6.0
  @see #getDnsTtlSuccessfulQueries()