多项选择题
A. when they receive a special token
B. when there is a carrier
C. when they detect no other devices are sending
D. when the medium is idle
E. when the server grants access
多项选择题 By default, each port in a Cisco Catalyst switch is assigned to VLAN1. Which two recommendations are key to avoid unauthorized management access?（）
多项选择题 Which of the following correctly describe steps in the OSI data encapsulation process?（）
多项选择题 Which three of these statements regarding 802.1Q trunking are correct?（）