200-101 · Question #51
200-101 Question #51: Real Exam Question with Answer & Explanation
The correct answer is B: 10.0.0.2 (Serial0.1), from 10.0.0.2, Send flag is 0x0 Composite metric is (53973248/128256), Route is Internal Vector metric: Minimum bandwidth is 48 Kbit Total delay is 25000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 1. In EIGRP, the feasible successor is a backup route that satisfies the Feasibility Condition (FC): the neighbor's Reported Distance (RD) must be strictly less than the local router's current Feasible Distance (FD) to the destination. First, identify the successor - the route with
Question
Options
- A10.1.0.3 (Serial0), from 10.1.0.3, Send flag is 0x0 Composite metric is (46866176/46354176), Route is Internal Vector metric: Minimum bandwidth is 56 Kbit Total delay is 45000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 2
- B10.0.0.2 (Serial0.1), from 10.0.0.2, Send flag is 0x0 Composite metric is (53973248/128256), Route is Internal Vector metric: Minimum bandwidth is 48 Kbit Total delay is 25000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 1
- C10.1.0.1 (Serial0), from 10.1.0.1, Send flag is 0x0 Composite metric is (46152000/41640000), Route is Internal Vector metric: Minimum bandwidth is 64 Kbit Total delay is 45000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 2
- D10.1.1.1 (Serial0.1), from 10.1.1.1, Send flag is 0x0 Composite metric is (46763776/46251776), Route is External Vector metric: Minimum bandwidth is 56 Kbit Total delay is 41000 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 2
Explanation
In EIGRP, the feasible successor is a backup route that satisfies the Feasibility Condition (FC): the neighbor's Reported Distance (RD) must be strictly less than the local router's current Feasible Distance (FD) to the destination. First, identify the successor - the route with the lowest composite metric (FD). That is option C with FD=46,152,000. Now check each remaining route's RD against 46,152,000: Option A has RD=46,354,176 (exceeds FC), Option B has RD=128,256 (satisfies FC), Option D has RD=46,251,776 (exceeds FC). Option B is the only route that passes the feasibility condition, making it the feasible successor. Its very low RD (128,256) indicates a short path reported by that neighbor, even though its total FD (53,973,248) is higher than the successor's.
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