Which of the following descriptions about exact matching switches and longest matching switches is correct?

Which of the following descriptions about exact matching switches and longest matching switches is correct?
A . The exact matching switch searches the routing table through software for packet-by-packet forwarding
B . The exact matching switch is to complete the forwarding of subsequent packets through hardware after the first packet is searched and processed by software, but it cannot cope with the impact of worms on routing
C . The longest matching switch uses software to search the routing table for
D . The longest matching switch replaces the software routing table with hardware entries, and follows the longest matching principle when searching. In the case of extremely serious network worms, it can still guarantee the wire-speed forwarding of IP packets

Answer: BD