如何判断计算机是否连接到inertnet,如果没有调用系统的拨号连接？

Check Internet Connection by
http://www.c-sharpcorner.com/Code/2003/Aug/CheckInternetConnection.asp
How to Detect a Dialup Connection?
http://www.c-sharpcorner.com/Code/2003/May/DetectingDialUpConnection.asp