Routing

Default Routes

Learn how routers use a default route as a fallback, how Cisco represents and selects one, and how it differs from other gateway and routing-protocol options.

Intermediate12 min read
Routing lessonNetworkingPractice

UNTIMED COACHING

Practice before the pressure

Use feedback to correct the model, not merely memorize an option position.

GUIDED PRACTICE

Practice the lesson questions

Answer normal lesson questions without a timer. Every answer includes an explanation, and incorrect answers can be tried again before continuing.

CONCEPT MODELS

See the lesson as a system

Use these visual guides to connect the key ideas before answering the questions.

Default route lookupRouters prefer specific matches, then use a broad fallback.
Default route lookupA destination lookup compares specific and default routes before forwarding.
Packet destinationAddress carried by the packet
Specific routeNarrow matching network entry
Default routeBroad fallback route entry
Forward packetSelected next-hop forwarding
Cisco default-route choicesCisco commands address routing-table defaults, disabled routing, and propagation.
Cisco default-route choicesThree Cisco configuration ideas lead to different default-routing outcomes.
IP routing enabledRouter performs route lookups
Static defaultConfigured all-destination route
IP routing disabledDevice uses management gateway
Default gatewayGateway for nonrouting device
Selecting a defaultCandidate defaults are compared using route-selection information.
Selecting a defaultCandidate networks are evaluated and the selected gateway appears in route display.
Candidate networksLists networks in the routing table
Compare candidatesUse distance and metric
Selected defaultCurrent gateway of last resort
Route displayPrivileged route information