The remote destination
A device does not need the whole path at once.
A device looks up the destination IP (Internet Protocol) address in its routing table. A matching on-link route allows direct delivery; otherwise, a route may select a next-hop router. The most-specific matching prefix is preferred.
The gateway is not the final destination. It is the next local router, which can inspect the packet and make the next forwarding decision.
A default route is a fallback, not a guarantee of Internet access. Without a usable route, delivery fails. DNS (Domain Name System) resolves names; it does not choose the next-hop router.
On Ethernet, the frame addresses the next-hop interface, while the packet still addresses the remote destination. Normal routing replaces the link-layer frame at each hop; network address translation (NAT) is a separate operation.
Build the model
Four useful roles
Local subnet
The address range where a device can deliver directly.
Default gateway
The next-hop router used by the default route.
Router
Connects networks and chooses a next hop for traffic.
Remote network
A destination range that cannot be reached directly on the current link.
Mini experiment
Choose the next step
Compare three routing decisions. The model assumes Ethernet delivery, usable next hops, and no competing policy rules.
Knowledge check