司法E通中矫正管理人员与矫正对象间的电话沟通频繁，通过综合（）服务，双方通过短号码进行互拨，方便记忆，同时能有效降低两者之间的通信成本。

A.VPN

B.VPDN

C.ISDN

D.PDSN

Every host and router on the Internet has an IP address, which encodes its

A．host number

B．host number and socket

C．network number

D．host number and network number