Networks can be interconnected by different devices in the physical layer networks can be connected by (71) or hubs．which just move the bits from one network to an identical network．One layer up we find bridges and switches which operate at data link layer．They can accept (72) ，examine the MAC address and forward the frames to a different network while doing minor protocol translation in the process in me network layer，we have routers that can connect two networks，If two networks have (73) network layer，the router may be able to translate betweenthe packer formats．In the transport layer we find transport gateway，which can interface between two transport connections Finally，in the application layer，application gateways translate message (74) ．As an example，gateways between Internet e-mail and X，400 e-mail must (75) thee-mail message and change various header fields．

A:syntax B:semantics C:language D:format

Networks can be interconnected by different devices in the physical layer networks can be connected by (71) or hubs．which just move the bits from one network to an identical network．One layer up we find bridges and switches which operate at data link layer．They can accept (72) ，examine the MAC address and forward the frames to a different network while doing minor protocol translation in the process in me network layer，we have routers that can connect two networks，If two networks have (73) network layer，the router may be able to translate betweenthe packer formats．In the transport layer we find transport gateway，which can interface between two transport connections Finally，in the application layer，application gateways translate message (74) ．As an example，gateways between Internet e-mail and X，400 e-mail must (75) thee-mail message and change various header fields．

A:analyze B:parse C:delete D:create

用32K×4位的RAM芯片构成256K×32位存储器芯片M，至少需要 (6) 个RAM芯片。若用构成的芯片M来存储16MB的内容，则至少需要 (7) 个这样的芯片M。

A:4 B:32 C:64 D:8

用32K×4位的RAM芯片构成256K×32位存储器芯片M，至少需要 (6) 个RAM芯片。若用构成的芯片M来存储16MB的内容，则至少需要 (7) 个这样的芯片M。

A:16 B:64 C:2 D:128

下面的______是ATM采用固定包大小方法的优点。

A:能够进行更有效的传输 B:能够提供更小的时间延迟 C:能够提供更高的安全性 D:能够更好地集成其他技术

从______开始，就完全是应用下层提供的可靠通信功能，而与纯通信无关。

A:传输层 B:会话层 C:表示层 D:应用层

计算机网络通信系统是______。

A:电信号传输系统 B:文字通信系统 C:信号通信系统 D:数据通信系统

一台主机要解析www.abc.edu.cn的IP地址，如果这台主机配置的域名服务器为202.120.66.68，因特网顶级域名服务器为11.2.8.6，而存储www.abc.edu.cn与其IP地址对应关系的域名服务器为202.113.16.10，那么这台主机解析该域名通常首先查询______。

A:202.120.66.68域名服务器 B:11.2.8.6域名服务器 C:202.113.16.10域名服务器 D:不能确定，可以从这三个域名服务器中任选一个

在双绞线组网的方式中，______是以太网的中心连接设备。

A:集线器 B:收发器 C:中继器 D:网卡

对局域网来说，网络控制的核心是______。

A:工作站 B:网卡 C:网络服务器 D:网络互连设备