Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A route to 10.10.20.0/24 disappears when an OSPF adjacency fails. Which design would most directly provide an automatic backup without changing the primary OSPF path during normal operation?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
A floating static route with a higher administrative distance than OSPF
This is correct because it provides a backup route without replacing OSPF under normal conditions.
B
Distractor review
A standard static route with the default administrative distance of 1
This is wrong because a default static route distance of 1 would override OSPF instead of floating behind it.
C
Distractor review
Removing OSPF entirely and using only a default route
This is wrong because it changes the primary design rather than preserving OSPF as the normal path.
D
Distractor review
Disabling the routing table on the router until failure occurs
This is wrong because routers do not work by disabling the routing table to create backup behavior.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting a standard static route with the default administrative distance of 1 as a backup. This causes the static route to override the OSPF route immediately, breaking the requirement that the primary OSPF path remains unchanged during normal operation. Candidates may overlook the importance of administrative distance in route selection, leading to incorrect answers. The trap exploits misunderstanding that static routes always act as backups, ignoring that their default preference is higher than OSPF’s, which disrupts routing behavior.
Technical deep dive
How to think about this question
OSPF (Open Shortest Path First) is a dynamic routing protocol that calculates the shortest path to each network based on link-state information. It uses a link-state database and Dijkstra’s algorithm to determine the best routes, which are then installed in the routing table with a default administrative distance of 110. When an OSPF adjacency fails, routes learned via OSPF are withdrawn, causing loss of connectivity unless a backup path exists. A floating static route is a static route configured with an administrative distance higher than that of OSPF, making it less preferred during normal operation. This means the router uses the OSPF-learned route as the primary path. If the OSPF route disappears due to adjacency failure, the floating static route automatically becomes active, providing seamless failover without manual intervention or disruption to the primary OSPF path. The exam trap lies in confusing static route administrative distances. A static route with the default administrative distance of 1 would override OSPF routes, disrupting normal routing behavior. Using a floating static route avoids this by ensuring OSPF routes remain preferred until they fail. This design is practical in Cisco networks for simple backup routing without redesigning the OSPF topology or relying on complex redistribution.
KKey Concepts to Remember
- OSPF uses a default administrative distance of 110 to install routes learned dynamically into the routing table.
- A floating static route is configured with an administrative distance higher than OSPF to act as a backup route.
- The router prefers OSPF routes over floating static routes during normal operation due to lower administrative distance.
- When an OSPF adjacency fails, the OSPF route is removed, allowing the floating static route to become active automatically.
- Static routes with default administrative distance override OSPF routes and disrupt the intended primary path.
- Using a floating static route preserves the OSPF primary path and provides automatic failover without manual intervention.
- OSPF adjacency failures cause route withdrawal, which triggers failover mechanisms like floating static routes.
- Backup routing designs must maintain primary routing protocol preference to avoid unintended route changes.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
OSPF uses a default administrative distance of 110 to install routes learned dynamically into the routing table.
What is the correct answer to this question?
The correct answer is: A floating static route with a higher administrative distance than OSPF — The most direct design is a floating static route with a higher administrative distance than OSPF. In plain language, that means the router keeps a manually configured backup route in reserve but does not use it while the OSPF route remains healthy. If the OSPF path disappears, the backup static route becomes active automatically. This is a very common and practical way to add simple failover. The key requirement in the question is that the primary OSPF path should remain unchanged under normal conditions. A normal static route with default distance would override OSPF and break that goal. A floating static route avoids that by staying less preferred until a failure occurs. That is why it is the correct design choice here.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
Loading comments…
Sign in to join the discussion.