A default gateway is which of the following?

• A. The IP address on a Layer 3 device that serves as an access point to/from a network
• B. The IP address of a host's NIC
• C. The MAC address of the router
• D. The broadcast address of the local subnet

Answer: (A)

A default gateway is the IP address on a Layer 3 device that serves as the access point to/from the local network. This address is the next hop a host uses to reach destinations outside its own subnet. When a host wants to send traffic to a non-local address, it sends the packet to this gateway’s IP, and the gateway (typically a router) forwards it toward the correct destination. It’s not the host’s own NIC IP, which identifies the host itself on the local network. It’s not the MAC address of the router, though the host will need to know the router’s MAC to deliver the frame on the local link; the gateway concept is defined by the IP address. It’s not the local broadcast address, which would reach every device on the subnet rather than specifying a next-hop for routing.