Recursive lookup management

build.gradle

@@ -54,6 +54,9 @@ dependencies {
     // DNS lookups
     compile 'dnsjava:dnsjava:2.1.8'
 
+    // Network utilities for recursive host check
+    compile 'commons-net:commons-net:3.5'
+
     testCompile 'junit:junit:4.12'
 }