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350-401 Practice Question: Which two statements about EIGRP feasible…
Which two statements about EIGRP feasible successors are true? (Choose two.)
⚠ Common exam trap
The trap is confusing the topology table with the routing table (feasible successors are not in the routing table) and misunderstanding the feasibility condition direction — candidates often think RD must be greater than FD or that a feasible successor is always available.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A feasible successor must have a reported distance less than the feasible distance.
Option A is correct because the feasibility condition requires that a neighbor's reported distance (RD, the neighbor's own metric to the destination) be strictly less than the local feasible distance (FD, the current best metric), which guarantees the path is loop-free. Option B is correct because a feasible successor is a pre-validated loop-free backup already held in the EIGRP topology table, so when the successor fails EIGRP can promote it instantly to the routing table without sending queries or entering Active state. Option C is wrong because the feasible distance is the metric of the current successor (the best route), not of the feasible successor. Option D is wrong because EIGRP does not guarantee a feasible successor exists for every route; if none satisfies the feasibility condition, the route goes Active and queries are sent. Option E is wrong because feasible successors are kept in the EIGRP topology table, not installed in the routing table, which holds only the best (successor) routes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A feasible successor must have a reported distance less than the feasible distance.
Why this is correct
The feasibility condition requires a neighbour's reported distance to be strictly lower than the local feasible distance. Meeting this guarantees the path is loop-free, which is exactly what qualifies that neighbour as a feasible successor and satisfies the stem's stated criterion.
- ✓
A feasible successor is immediately used when the successor fails, without any query process.
Why this is correct
Because a feasible successor already satisfies the feasibility condition, its path is guaranteed loop-free, so the router installs it into the routing table the instant the successor fails. No diffusing computation or query to neighbours occurs, giving near-instantaneous convergence.
- ✗
The feasible distance is the metric of the feasible successor route.
Why it's wrong here
Feasible distance is the metric of the route already installed in the routing table, not the feasible successor's metric; the feasible successor's advertised distance must be lower than that feasible distance. It tempts because feasible distance does derive from a successor route, but that successor is the current best path, not the backup.
- ✗
EIGRP will always have at least one feasible successor for every route.
Why it's wrong here
A route may have no feasible successor when no neighbour satisfies the feasibility condition, forcing EIGRP into active state and queries. It is tempting because feasible successors are common, and the statement would hold only where a neighbour's reported distance stays below the feasible distance.
- ✗
The feasible successor is stored in the routing table as a backup route.
Why it's wrong here
Feasible successors are held in the topology table, not installed in the routing table, which lists only successors. It is tempting because they do act as backups, and a route would appear in the routing table once promoted after the successor fails.
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.