Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A router learns the same destination prefix from OSPF and from a static route configured with administrative distance 90. Which route is preferred by default?
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
The static route with distance 90
This is correct because 90 is lower than OSPF’s default administrative distance of 110.
B
Distractor review
The OSPF route, because dynamic routes always beat static routes
This is wrong because route preference depends on administrative distance, not a simple dynamic-versus-static rule.
C
Distractor review
Both routes equally, because the prefix is identical
This is wrong because identical prefix length does not mean equal installation when the administrative distances differ.
D
Distractor review
Neither route, because duplicate information is dropped
This is wrong because the router can choose a preferred source for the same prefix.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is believing that dynamic routing protocols like OSPF always take precedence over static routes. Many candidates mistakenly think that dynamic routes inherently override static routes regardless of administrative distance. However, Cisco routers use administrative distance as the primary factor in route selection, not the route source type. Since the static route in this question has an AD of 90, which is lower than OSPF’s default 110, the static route is preferred. Misunderstanding this can lead to incorrect answers and confusion about route installation in the routing table.
Technical deep dive
How to think about this question
Administrative distance (AD) is a Cisco router feature that ranks the trustworthiness of routing information sources. Each routing protocol and route type has a default AD value, with lower values indicating more preferred routes. Static routes have a default AD of 1, but this can be manually adjusted to any value between 0 and 255. OSPF, a dynamic link-state routing protocol, has a default AD of 110. When a router learns the same prefix from multiple sources, it uses AD to decide which route to install in the routing table. When a router receives identical destination prefixes from OSPF and a static route configured with an AD of 90, it compares the AD values directly. Since 90 is lower than OSPF’s default 110, the router prefers the static route despite OSPF being a dynamic protocol. The router installs the static route in the routing table and forwards traffic accordingly. This behavior highlights that administrative distance, not route type (static vs. dynamic), determines route preference. A common exam trap is assuming dynamic routing protocols always override static routes. This is incorrect because AD values can be tuned, changing route preference. In practice, network engineers adjust static route ADs to influence routing decisions, such as preferring a static backup route over a dynamic one. Understanding this nuance is critical for CCNA candidates to avoid misinterpreting route selection behavior in Cisco routers.
KKey Concepts to Remember
- Cisco routers use administrative distance to determine the trustworthiness of routing information sources when multiple routes to the same prefix exist.
- A lower administrative distance value indicates a more preferred route that the router installs in the routing table.
- Static routes have a default administrative distance of 1 but can be manually configured to any value between 0 and 255 to influence route preference.
- OSPF has a default administrative distance of 110, which is higher than the configured static route AD of 90 in this scenario.
- When identical prefixes are learned from OSPF and a static route with AD 90, the router prefers the static route due to its lower administrative distance.
- Route preference depends on administrative distance values, not on whether the route is static or dynamic by default.
- Cisco routers install only one best route per prefix in the routing table based on the lowest administrative distance.
- Adjusting administrative distance on static routes is a common practice to override dynamic routing protocol preferences for specific traffic engineering needs.
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.
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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?
Cisco routers use administrative distance to determine the trustworthiness of routing information sources when multiple routes to the same prefix exist.
What is the correct answer to this question?
The correct answer is: The static route with distance 90 — The static route is preferred because its administrative distance of 90 is lower than OSPF’s default administrative distance of 110. In practical terms, when the prefix length is the same, the router compares route-source trust next. The lower administrative distance wins. This question is important because many learners remember that static routes are often strong choices but forget that administrative distance can be tuned. Here, that tuning explicitly makes the static route more preferred than OSPF.
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.
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