4.Which of the following switching methods receives the entire frame,computes the CRC,and then forwards the frame?
Cut-through(直通式)
Fragment-free(碎片隔离式)
Store-and-forward(存储转发式)
Cell-relay(信元交换)
Store-and-forward（存储转发）会接收完整的帧，进行CRC校验，确认无误后再转发，延迟较高但最可靠。