optimize system dns

Author: YangSen-qn

.idea/modules.xml

@@ -9,7 +9,11 @@
 import java.util.Date;
 import java.util.List;
 import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Future;
 import java.util.concurrent.FutureTask;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 /**