1. [单选题]在OSPF的DR/BDR选举过程中，在路由器有相同的接口优先级情况下，什么用于确定DR或BDR（）
A. 最高的OSPF进程ID
B. 最低的接口IP地址
C. 最低的接口开销
D. 路由器ID
2. [多选题]Which of the following statements correctly describe the differences between half-duplex and full-duplex Ethernet? (Select two answer choices.)
A. Full-duplex Ethernet uses CSMA/CD to prevent collisions.
B. Half-duplex Ethernet uses a loopback circuit to detect collisions.
C. A full-duplex Ethernet card allows 20Mbps for data transmission.
D. Full-duplex Ethernet makes use of two pairs of wires for data.
E. An Ethernet hub can operate both half and full duplex simultaneously.
3. [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
4. [单选题]EIGRP的管理距离（）
A. 90
B. 100
C. 110
D. 120
5. [多选题]Which of the following are types of flow control? (Choose three)
A. Buffering
B. Cut-through
C. Windowing
D. Congestion avoidance
E. Load balancing
