在cmd中运行ping www.baidu.com 什么意思，有什么用呀

检查你的网络是否连接正常

C:\Documents and Settings\Mary>ping www.baidu.com

Pinging www.a.shifen.com [220.181.6.6] with 32 bytes of data:

Reply from 220.181.6.6: bytes=32 time=210ms TTL=54
Reply from 220.181.6.6: bytes=32 time=214ms TTL=54
Reply from 220.181.6.6: bytes=32 time=213ms TTL=54
Reply from 220.181.6.6: bytes=32 time=209ms TTL=54

Ping statistics for 220.181.6.6:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 209ms, Maximum = 214ms, Average = 211ms

C:\Documents and Settings\Mary>

向百度发送数据包，然后再返回

是看他通过几个路由器吧