Router A has an EIGRP route with successor via R2 and an advertised feasible successor via R3. The link to R2 fails. Which outcome best describes DUAL behavior on Router A?

EIGRP's DUAL (Diffusing Update Algorithm) is designed for fast convergence. When the primary successor (via R2) fails, and a feasible successor (via R3) already meets the feasibility condition (its reported distance is less than the current feasible distance), DUAL immediately promotes the feasible successor to the new successor. This allows Router A to update its routing table and forward traffic via R3 without delay, avoiding a re-computation or query process. Entering the active state (and sending queries) only happens if no feasible successor exists. Dropping the route or waiting for a timeout would introduce significant delays, which EIGRP aims to prevent.