5.In Spanning Tree Protocol(STP),what is the port state where the port does not participate in frame forwarding but still receives BPDUs to detect topology changes?
Forwarding
Learning
Blocking
Disabled
在STP中，Blocking（阻塞）状态的端口不转发数据帧，也不学习MAC地址，但仍然接收BPDU报文以便监控网络拓扑。