Final answer:
The destination address that PC1 will include in the Ethernet frame sent to PC2 is PC2's MAC address, which it obtains either from its Address Resolution Protocol (ARP) table or via an ARP request if necessary.
Step-by-step explanation:
The question pertains to how a PC (Personal Computer) determines the destination address to include in an Ethernet frame when it needs to send data to another PC in a local network. If PC1 wants to send data to PC2, it will inspect its Address Resolution Protocol (ARP) table to find the corresponding Ethernet (MAC) address for PC2. If the MAC address is not found or the table does not contain an entry for PC2, PC1 will broadcast an ARP request to all devices on the network asking who has PC2's IP address. Once an ARP reply with PC2's MAC address is received, PC1 will use this address in the destination address field of the Ethernet frame it sends to PC2. If PC2 is on a different network, PC1 will send the Ethernet frame to the default gateway's MAC address, and then routing will take place to reach PC2.