Final answer:
The sending node uses the MAC address of the default gateway when addressing a packet to a remote network, as it cannot directly communicate with devices outside its local area network.
Step-by-step explanation:
When a packet is addressed to a remote network, the sending node will use the MAC address of the default gateway. The default gateway is typically your local router, which is responsible for forwarding packets out of the local network towards the destination network. This is necessary because the sending node does not have the capacity to directly communicate with the MAC address of devices outside its local network, so it relies on the gateway to route the information appropriately.