264、The data link layer provides services to the network layer on the basis the services provided by the physical layer.

358、Maintenance begins after the system is released.As people use i t, they will suggest minor improvements and enhancements.Occasionally, bugs slip through debug and testing, and removing them is another maintenance task.

357、Positioning your firewall between an internal and external router provides little additional protection from attacks on either side, but it greatly reduces the amount of traffic the firewall server must evaluate, which can increase the firewall＇ s performance.

356、近年来,随着因特网覆盖范围的扩展,引人了一组国

355、.RF网络所用的天线在物理上可大可小,这取决于所需的通信范围。

354、检索数据的关键是记住数据存放在什么地方

353、人类不必像计算机一样地思

352、双绞线的最普通的应用是电话

351、client

350、orbit

349、semiconductor