1. [单选题]The Ezonexam network administrator has just issued the "switchport trunk native vlan 998" command on switch VE2. What is the function of this command?
A. It designates VLAN 998 as the default for all unknown tagged traffic
B. It designates VLAN 998 for untagged traffic
C. It blocks VLAN 998 traffic from passing on the trunk
D. It creates a VLAN 998 interface
E. None of the above
2. [单选题]帧中继环境中，CIR的含义是（）
A. 提高线路速率
B. 保证线路速率
C. 降低线路速率
D. 配置线路速率
