You want to log into the router and make a configuration change.After loggin in as the root user, what is the next command you must enter?（）

单项选择题What is the operating system do Juniper Networks MX Series routers use?（）

A. IOS
B. MX-OS
C. UNIX
D. Junos OS

单项选择题What information does the help reference command provide?（）

A. a brief description of commands and their default values
B. the serial number and version number of the device used to open a support case with JTAC
C. a list of all the active hardware alarms on the device
D. a display of the current configuration while in operational mode

单项选择题You have been allocated a 192.168.100.0 22 network. How many usable host are available?（）

A. 510
B. 512
C. 1022
D. 1024

单项选择题What represents the decimal equivalence of 01101110?（）

A. 5
B. 96
C. 110
D. 118

单项选择题Which network mask is the equivalent of 255.255.248.0?（）

A. /20
B. /21
C. /22
D. /23