200-101 · Question #212
Refer to the exhibit. What address is a feasible successor?
The correct answer is C. 10.1.2.2. In EIGRP, a feasible successor is a backup route whose Reported Distance (RD) is less than the current successor's Feasible Distance (FD), satisfying the feasibility condition. The next-hop 10.1.2.2 meets this criterion based on the topology table shown.
Question
Exhibit
Options
- A172.16.4.0
- B10.1.4.2
- C10.1.2.2
- D172.16.3.0
How the community answered
(49 responses)- A2% (1)
- B8% (4)
- C84% (41)
- D6% (3)
Why each option
In EIGRP, a feasible successor is a backup route whose Reported Distance (RD) is less than the current successor's Feasible Distance (FD), satisfying the feasibility condition. The next-hop 10.1.2.2 meets this criterion based on the topology table shown.
172.16.4.0 is a destination network prefix, not a next-hop address used to identify a feasible successor in the EIGRP topology table.
10.1.4.2 is a next-hop address but its Reported Distance does not satisfy the feasibility condition (RD is not less than the successor's FD), so it cannot serve as a feasible successor.
The next-hop address 10.1.2.2 satisfies the EIGRP feasibility condition - its Reported Distance is strictly less than the Feasible Distance of the current successor path. This qualifies it as a feasible successor, meaning it is pre-computed as a loop-free backup and is stored in the topology table ready for instant failover without requiring a new DUAL computation.
172.16.3.0 is a destination network prefix, not a next-hop address, and therefore cannot be a feasible successor next-hop.
Concept tested: EIGRP feasibility condition and feasible successor identification
Source: https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/13669-1.html
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