单项选择题
A. A command that is available in every release of IOS, regardless of the version or deployment status.
B. A command that can be entered in any configuration mode.
C. A command that is universal in application and supports all protocols.
D. A command that is implemented in all foreign and domestic IOS version.
E. A command that is set once and affects the entire router.
单项选择题 What feature of a networks switch allows an administrative to create separate broadcast domains?（）
单项选择题 Which of the following options lists the steps in PPP session establishment in the correct order?（）
单项选择题 Which Frame Relay feature is responsible for transmitting keepalives to ensure that the PVC does not shut down because of inactivity?（）