[单项选择]OSI (Open System Interconnection)安全体系方案X.800将安全性攻击分为两类，即被动攻击和主动攻击。主动攻击包括篡改数据流或伪造数据流，这种攻击试图改变系统资源或影响系统运行。下列攻击方式中不属于主动攻击的为______。
A. 伪装
B. 消息泄露
C. 重放
D. 拒绝服务

[单项选择]OSI（Open System Interconnection）安全体系方案X.800将安全服务定义为通信开放系统协议层提供的服务，用来保证系统或数据传输有足够的安全性。X.800定义了5类可选的安全服务。下列相关的选项中不属于这5类安全服务的是（）。
A. 数据保密性
B. 认证
C. 访问控制
D. 数据压缩

[单项选择]OSI安全体系方案X.800将安全性攻击分为两类，即被动攻击和主动攻击，主动攻击包括篡改数据流或伪造数据流，这种攻击试图改变系统资源或影响系统运行。下列攻击方式中不属于主动攻击的为______。
A. 伪装
B. 消息泄漏
C. 重放
D. 拒绝服务

[单项选择]TCP functions at the Open System Interconnection (OSI) (61) layer, or Layer 4. Its chief responsibility is to ensure (62) end-to-end connectivity. IP, located one layer down, at the OSI network layer, or Layer 3, communicates the addresses of each (63) sender and receiver to the routers along the way. Routers and Layer 3 switches can read IP and other Layer 3 (64) . This information, combined with routing tables and other network intelligence, is all it takes to get (65) the room or around the world via TCP/IP.

A. transpose
B. translate
C. transmit
D. transport

[单项选择]

In the open systems interconnection (OSI) reference model, "layer" means one of seven conceptually complete, (71) arranged groups of services, functions, and protocols, that extend across all open systems.
Application layer provides means for the application (72) to access the OSI environment. Presentation layer provides for the selection of a common syntax for representing data. (73) layer provides the means necessary for cooperating presentation entities to organize and synchronize their dialog and to manage their data exchange. Transport layer provides a reliable end-to-end data transfer service. Network layer provides for the entities in the transport layer the means for transferring blocks of data, by (74) and switching through the network between the open systems in which those entities reside. Data link layer provides services to transfer data between network layer entities. Physical layer provides the mechanical, electr
A. Conversation
B. Dialog
C. Session
D. Discussion