What Is a Default Route?
a Default Route — a catch-all route (0.0.0.0/0) that a router uses for any destination not specifically listed in its routing table — typically pointing toward the internet.
How it works
When a packet's destination matches no specific route, the default route catches it — sending it to a "gateway of last resort", usually the ISP or a core router. Written as 0.0.0.0/0 (it matches everything, but with the shortest possible prefix so specific routes always win first via longest-prefix match).
Why it matters
Default routes keep routing tables small and simple — an edge router doesn't need every internet route, just "send unknown traffic this way". Configuring one (ip route 0.0.0.0 0.0.0.0 next-hop) is among the first things on any internet-facing router. See the routing table guide.
Frequently asked questions
What is a default route?
A catch-all route (0.0.0.0/0) used for any destination not otherwise in the routing table — usually directing unknown traffic toward the internet.
Why doesn't the default route override specific routes?
Longest-prefix match — the default route's /0 is the shortest possible prefix, so any more specific matching route is always preferred first.
How do you configure a default route?
ip route 0.0.0.0 0.0.0.0
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