CCNA IP Routing Practice Question
R1 loses its route to 192.168.20.0/24 whenever R2's GigabitEthernet0/0 interface flaps. The network engineer has configured a floating static route with an administrative distance of 200. The OSPF route has an AD of 110. After R2's G0/0 interface recovers, the floating static route appears in the routing table instead of the OSPF route. What should the technician do next?
⚠ Common exam trap
Cisco often tests the concept that a floating static route can persist after a link recovers due to interface timers (carrier delay) delaying OSPF convergence, leading candidates to mistakenly focus on administrative distance adjustments or clearing the routing table.
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
✓
Check the carrier delay timers on R2's GigabitEthernet0/0 interface.
When R2's GigabitEthernet0/0 interface flaps, the OSPF neighbor relationship goes down, causing R1 to lose the OSPF route. The floating static route (AD 200) then takes over. After the interface recovers, OSPF should re-establish and install its route (AD 110) over the static route. However, if the carrier delay timer on R2's interface is set too high, the interface may not come up quickly enough for OSPF to re-converge before the floating static route is already installed and preferred. Checking and adjusting the carrier delay timer ensures that the interface state change is propagated promptly, allowing OSPF to re-establish and replace the static route.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Adjust the administrative distance of the floating static route to 201.
Why it's wrong here
The AD is already 200, which is higher than OSPF’s 110, so this change would not prevent OSPF from taking over once it converges. The issue is not the AD but that OSPF is not re‑installing its route.
- ✓
Check the carrier delay timers on R2's GigabitEthernet0/0 interface.
Why this is correct
A high carrier-delay (interface debounce) timer can keep the link down for too long after a flap, delaying OSPF neighbor formation. While the interface remains down, the floating static route stays in the table. Checking this timer is a logical, non‑destructive next step.
- ✗
Clear the IP routing table and reset the OSPF process on R1.
Why it's wrong here
Clearing the routing table and resetting OSPF is a drastic action that temporarily restores OSPF routes but does not address the underlying reason OSPF failed to converge. It should only be used after confirming the root cause.
- ✗
Verify that the MTU on R1 and R2's GigabitEthernet0/0 interfaces match.
Why it's wrong here
An MTU mismatch would cause OSPF to be stuck in Exstart/Exchange state, but this would be a persistent problem, not one triggered exclusively by a flap. The described symptom points to a convergence delay, not a permanent adjacency issue.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Check the carrier delay timers on R2's GigabitEthernet0/0 interface.Correct answer▾
Why this is correct
A high carrier-delay (interface debounce) timer can keep the link down for too long after a flap, delaying OSPF neighbor formation. While the interface remains down, the floating static route stays in the table. Checking this timer is a logical, non‑destructive next step.
✗Adjust the administrative distance of the floating static route to 201.Wrong answer — click to see why▾
Why this is wrong here
Misunderstanding of route preference: a higher AD value does not keep a floating static installed when a better OSPF route becomes available.
✗Clear the IP routing table and reset the OSPF process on R1.Wrong answer — click to see why▾
Why this is wrong here
Troubleshooting should follow the OSI model bottom‑up; immediately resetting processes skips basic interface‑level verification.
✗Verify that the MTU on R1 and R2's GigabitEthernet0/0 interfaces match.Wrong answer — click to see why▾
Why this is wrong here
It targets a different root cause (OSPF adjacency failure due to MTU) that would manifest constantly, not only after interface recovery.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
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.
Go deeper
Related to this question
Learn chapter
Interpreting HSRP and VRRP Operational Status
Key term
Routing table
A routing table is a data set stored in a router or host that contains information about network paths and is used to determine where to forward data packets.
Key term
ISP
An ISP is a company that provides individuals and organizations access to the Internet, along with related services like email and web hosting.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.