Ping any given IP address (given in dot notation).
ping任意给定IP地址。
The ping operation is asynchronous and a ping object can be polled for status using Ping.isDone. When a response is received it is in Ping.time.
ping操作是异步的并且ping可以使用Ping.isDone查询状态。一个响应在Ping.time时间被接收。