Routing and Path Selection
- Explain routing tables, next hops, and path decisions
- Apply the idea to evidence from a realistic technology scenario
- Justify a decision using security, reliability, cost, and user impact
Routing and Path Selection
Routers compare a destination address with routing-table prefixes and choose the most specific matching route. A route identifies a next hop or outgoing interface. Dynamic routing protocols exchange reachability, while a default route handles destinations with no more specific entry.
Decision lens
Strong technical decisions connect evidence → mechanism → impact → response. Identify what the evidence shows, explain the system behavior that produced it, state the likely effect on people or data, and choose a response that addresses the cause without creating unnecessary disruption.
A router knows 10.20.0.0/16 through gateway A and 10.20.5.0/24 through gateway B. A packet targets 10.20.5.90.
- 1.Both routes match the destination.
- 2.The /24 prefix is more specific than /16.
- 3.Longest-prefix matching selects gateway B.
- 4.Route cost matters among comparable routes, not instead of prefix specificity.
What does a default route represent?
Which response best demonstrates complete reasoning about routing tables, next hops, and path decisions?
For a scenario about routing tables, next hops, and path decisions, identify the decisive evidence before naming a response. A defensible conclusion here is: The router forwards through gateway B using the /24 route.
Answer the 2 checkpoints as you read.
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