Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
R1 interface to LAN: 192.168.50.1/24 on G0/1 R1 OSPF config: router ospf 1 network 192.168.5.0 0.0.0.255 area 0 network 10.0.12.0 0.0.0.3 area 0
Exhibit: R2 has no route to 192.168.50.0/24 even though R1 advertises it in OSPF. Which issue in the exhibit best explains the problem?
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
The OSPF process must be process ID 50 to advertise 192.168.50.0/24
Distractor.
B
Best answer
The wildcard network statement does not match 192.168.50.0/24
Correct choice.
C
Distractor review
OSPF cannot advertise a directly connected LAN
Distractor.
D
Distractor review
R2 needs a default route before learning intra-area routes
Distractor.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is believing that the OSPF process ID must match across routers to advertise specific networks or that OSPF cannot advertise directly connected LANs. Candidates may also incorrectly assume that a default route is required on a router before it can learn intra-area routes. These misconceptions lead to overlooking the actual cause: a mismatched wildcard mask in the network statement that prevents OSPF from activating on the interface. This trap causes candidates to focus on irrelevant configuration elements instead of verifying the network statement accuracy.
Technical deep dive
How to think about this question
Open Shortest Path First (OSPF) is a link-state routing protocol that relies on interfaces being explicitly included in the OSPF process via network statements. These network statements use IP address and wildcard mask pairs to identify which interfaces participate in OSPF. The wildcard mask is a bitwise inverse of a subnet mask and determines which bits of the IP address must match exactly and which bits can vary. This mechanism allows precise control over which interfaces are advertised in OSPF. When configuring OSPF on Cisco routers, the network statement must correctly match the IP address of the interface connected to the subnet intended for advertisement. If the wildcard mask is incorrect or does not cover the interface's IP address, OSPF will not activate on that interface, and the subnet will not be advertised to neighbors. This prevents other routers from learning routes to that subnet, causing routing failures even though OSPF is running on other interfaces. A common exam trap is assuming that the OSPF process ID or the nature of the subnet (such as being directly connected) affects route advertisement. In reality, the process ID is locally significant and does not impact route advertisement between routers. Also, directly connected LANs are advertised if included in the OSPF process. The practical implication is that network engineers must carefully verify wildcard masks in OSPF configurations to ensure all intended subnets are advertised and reachable across the OSPF domain.
KKey Concepts to Remember
- OSPF uses network statements with wildcard masks to determine which interfaces participate in the OSPF routing process and advertise their connected subnets.
- A wildcard mask in OSPF network statements specifies which bits of the IP address to ignore, allowing flexible matching of interface IP addresses.
- If the OSPF network statement does not match an interface's IP address, OSPF will not enable on that interface and will not advertise its subnet.
- OSPF routers advertise only those networks explicitly included by matching network statements in the OSPF configuration.
- OSPF process ID is locally significant and does not affect the ability to advertise specific networks between routers.
- Directly connected LANs can be advertised in OSPF if their interfaces are included in the OSPF network statements.
- OSPF does not require a default route to learn intra-area routes; it learns routes from neighbors based on LSAs and area topology.
- Incorrect wildcard masks in OSPF configurations are a common cause of missing routes in OSPF neighbor routing tables.
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 network statements with wildcard masks to determine which interfaces participate in the OSPF routing process and advertise their connected subnets.
What is the correct answer to this question?
The correct answer is: The wildcard network statement does not match 192.168.50.0/24 — If the network statement on R1 does not match the interface connected to 192.168.50.0/24, OSPF will not enable on that interface and the subnet will not be advertised. The route stays absent from neighbors despite OSPF running elsewhere.
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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