软件水平考试

【单选题】Most IP layer-based proxy mechanisms, such as network address translation (NAT), only support uni-directional proxy, from the internal network to external network (the Internet). The proxy establishes the communication channel by (66) IP addresses. The IP addresses must be (67) . These proxy mechanisms prevent applications that must establish return data channels from establishing their data channels, such as, multimedia applications. IP layer-based proxy mechanisms need additional software (68) for each application that uses (69) channels. SOCKS identifies communication targets through domain names, overcoming the restriction of using private IP addresses. SOCKS can use domain names to establish communication between separate LANs, with (70) IP addresses.

A、duplicating
B．overlapping
C．crossing
D．repeating

网考网参考答案：B
网考网解析：
[参考译文] 所有的基于IP层的代理机制(例如，网络地址转换(NAT))，仅仅支持从内部网到外部网(因特网)单方向代理，代理通过操纵IP地址来建立通信链路。IP地址必须由通路而定义。这些代理机制阻止了那些在建立数据通道的过程中必须建立自己的返回数据链路的应用，例如多媒体应用软件。基于IP层的代理机制需要为每一个需要多通道的应用程序提供额外的软件模块。套接字通过域名来识别通信目标，克服了使用私有IP地址的限制。套接字能够用域名在不同的局域网中建立通信，即便使用相同的IP地址。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>