400-007 Question #95: Real Exam Question with Answer & Explanation

The correct answer is D: Redistribute the external prefixes onto OSPF and ensure that the total metric calculation includes. Hot-potato routing is a strategy where a router forwards traffic to the nearest exit point as quickly as possible, minimizing how long the traffic travels within the local network. In OSPF, this is achieved by redistributing external prefixes into OSPF and ensuring the total metr

Question

Company XYZ runs OSPF in their network. A design engineer decides to implement hot-potato routing architecture. How can this implementation be achieved?

Options

AEnable iBGP and apply prepend to ensure all prefixes will have the same length of the AS path
BRedistribute the external prefixes onto OSPF and ensure the total metric calculation includes only
CEnable OSPF load-balancing over unequal cost path.
DRedistribute the external prefixes onto OSPF and ensure that the total metric calculation includes

Explanation

Hot-potato routing is a strategy where a router forwards traffic to the nearest exit point as quickly as possible, minimizing how long the traffic travels within the local network. In OSPF, this is achieved by redistributing external prefixes into OSPF and ensuring the total metric calculation includes both the internal OSPF cost to reach the exit point (ASBR) and the external metric - so each router selects the exit door based on the full path cost. This naturally causes ingress routers to prefer the closest exit, which is the definition of hot-potato routing. Option A is incorrect because iBGP AS-path prepending is a BGP mechanism unrelated to OSPF-based hot-potato. Option B describes a metric calculation that likely excludes components needed for true hot-potato behavior. Option C describes OSPF unequal-cost load balancing (which OSPF does not natively support without specific extensions), which is a different concept entirely.

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