In the figure, a web client sends an HTTP request to a web server, and...

A router works mainly at the network layer . When it receives a frame, it removes the Layer 2 header and trailer, examines the destination IP address in the Layer 3 header, consults the routing table, selects the outgoing interface, and then re-encapsulates the packet into a new Layer 2 frame for the next hop. Therefore, statement B is true and is not part of the answer.

Statement A is false because the router does not create a new destination IP address during normal forwarding. The source and destination IP addresses remain unchanged end to end unless special functions such as NAT are used. Statement C is false because routing-table lookup is based on the destination IP address, not on TCP or UDP port numbers. Statement D is also false because normal IP routing does not inspect application-layer content to determine the outgoing interface. That decision is made from the network-layer destination address and the routing table. This question tests the layered forwarding logic of routers in TCP/IP networks.

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