1. [单选题]What is the purpose of the Spanning Tree Protocol (STP)?
A. To prevent routing loops
B. To create a default route
C. To provide multiple gateways for hosts
D. To maintain a loop-free Layer 2 network topology
E. To enhance the functions of SNMP
2. [单选题]You want to upgrade the Ezonexam LAN so that all ports operate in full duplex mode. Which statement is true about full-duplex Ethernet when comparing to half-duplex Ethernet?
A. Full-duplex Ethernet consists of a shared cable segment. Half-duplex provides a point-to-point link
B. Full-duplex Ethernet uses two wires to send and receive. Half-duplex Ethernet uses one wire to send and receive
C. Full-duplex Ethernet can provide higher throughput than can half-duplex Ethernet of the same bandwidth
D. Full-duplex Ethernet uses a loopback circuit to detect collisions. Half-duplex Ethernet uses a jam signal
E. None of the above
3. [多选题]请选出交换机处理帧的三种模式：()
A. 直通模式
B. 存储转发模式
C. 侦测模式
D. 分段模式
E. 阻塞模式
