Question 1hardmultiple choice
Full question →R1 learns three OSPF routes to different destinations:
O 10.10.10.0/24
O IA 10.20.20.0/24 O E2 10.30.30.0/24
Which statement is correct about these route types?
hardmultiple choiceObjective-mapped
R1 learns three OSPF routes to different destinations:
O 10.10.10.0/24
O IA 10.20.20.0/24 O E2 10.30.30.0/24
Which statement is correct about these route types?
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
Distractor review
O IA is an external route redistributed from another routing protocol.
O IA means interarea, not external.
B
Best answer
O E2 is an OSPF external type 2 route.
That is exactly what the code means.
C
Distractor review
O means the route was learned through EIGRP.
O is an OSPF code.
D
Distractor review
All three routes were learned from the same OSPF area type.
They represent different route origins inside or outside the OSPF domain.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is confusing the OSPF route codes, especially mistaking 'O IA' (inter-area) for an external route redistributed from another protocol. Candidates often incorrectly assume that 'O IA' means external, but it actually represents routes learned from a different OSPF area within the same autonomous system. Another common mistake is thinking the 'O' code indicates EIGRP routes, which it does not; EIGRP uses different codes such as 'D'. This confusion can cause candidates to select incorrect answers about route origins or types. Carefully distinguishing between intra-area, inter-area, and external routes based on OSPF codes is essential to avoid this pitfall.
Technical deep dive
How to think about this question
OSPF (Open Shortest Path First) is a link-state routing protocol that categorizes routes based on their origin within the OSPF domain or from external sources. The route codes seen in the routing table provide insight into how OSPF learned each route: 'O' indicates an intra-area route learned within the same OSPF area; 'O IA' stands for inter-area routes learned from a different OSPF area within the same autonomous system; and 'O E2' represents external type 2 routes that are redistributed into OSPF from other routing protocols or external sources. When OSPF redistributes external routes, it classifies them as either type 1 (E1) or type 2 (E2) external routes. Type 2 external routes (O E2) carry a fixed external cost that does not increase as the route is propagated through the OSPF domain, making them distinct from intra-area and inter-area routes. The routing table codes help network engineers quickly identify the route origin and metric type, which is crucial for understanding route preference and path selection in Cisco routers. A common exam trap is confusing the OSPF route codes with those of other protocols or misinterpreting the meaning of 'O IA' as an external route. For example, 'O IA' means inter-area within OSPF, not external redistribution. Also, the 'O' code does not indicate EIGRP routes; EIGRP uses a different code. Understanding these distinctions helps avoid misreading routing tables and selecting incorrect answers on the CCNA exam. Practically, knowing these codes aids in troubleshooting OSPF routing issues and optimizing route redistribution strategies.
KKey Concepts to Remember
- OSPF uses route codes in the routing table to indicate the origin and type of each learned route, such as intra-area, inter-area, or external.
- An 'O' route in OSPF is an intra-area route learned within the same OSPF area and has the lowest administrative distance among OSPF routes.
- 'O IA' routes represent inter-area routes learned from a different OSPF area within the same autonomous system, not external routes.
- 'O E2' routes are OSPF external type 2 routes that have been redistributed from other routing protocols or external sources into OSPF.
- OSPF external type 2 routes carry a fixed external cost that does not increase as the route propagates through the OSPF domain.
- EIGRP routes use different routing codes and are not represented by 'O' or 'O IA' in the routing table, which are specific to OSPF.
- Understanding OSPF route codes helps network engineers quickly identify route origins and make informed routing decisions in Cisco environments.
- Misinterpreting OSPF route codes can lead to incorrect assumptions about route origin and metric, which is a common exam trap in CCNA routing questions.
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?
OSPF uses route codes in the routing table to indicate the origin and type of each learned route, such as intra-area, inter-area, or external.
What is the correct answer to this question?
The correct answer is: O E2 is an OSPF external type 2 route. — An O route is intra-area, O IA is interarea, and O E2 is an external type 2 route redistributed into OSPF. The codes describe route origin, not just preference. CCNA expects you to identify them quickly when reading the routing table.
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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