多项选择题
Which two commands allow you to return to a previous verision of software on the device?（）
A. request sytem software add B. request sytem software downgrade C. request sytem software replace D. request sytem software rollback
单项选择题 Which statement is true regarding the Junos OS?（）
单项选择题 What must be configured prior to the first commit after factory defaults are loaded?（）
多项选择题 Which two fields are found in an Ethernet frame header?（）
