A router receives an incoming packet and determines that the destination host is located on a LAN directly attached to one of the router interfaces. Which destination address will the router use to encapsulate the Ethernet frame when forwarding the packet?

The router will use the MAC (Media Access Control) address of the destination host to encapsulate the Ethernet frame when forwarding the packet. Here are the steps:

1. The router receives the incoming packet and reads the destination IP address.
2. The router checks its routing table to determine the next hop for the packet. In this case, the destination host is on a directly attached LAN, so the next hop is the destination host itself.
3. The router then needs to find out the MAC address of the destination host. It does this by checking its ARP (Address Resolution Protocol) cache. If the MAC address is in the cache, it uses that. If not, it sends an ARP request to the LAN to find out the MAC address of the destination host.
4. Once the router has the MAC address, it encapsulates the IP packet into an Ethernet frame. The destination MAC address in the Ethernet frame is the MAC address of the destination host.
5. The router then sends the Ethernet frame onto the LAN. The destination host receives the frame, decapsulates the IP packet, and processes it.