Question 1mediummulti select
Full question →mediummulti selectObjective-mapped
Which two statements accurately describe passive interfaces in OSPF?
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
It suppresses OSPF hello packets on that interface.
This is correct because passive interfaces do not actively form OSPF neighbors.
B
Best answer
It can still allow the connected network to be advertised into OSPF.
This is correct because passive affects adjacency formation, not necessarily advertisement of the network.
C
Distractor review
It converts OSPF on that interface into static routing.
This is wrong because passive-interface does not change OSPF into static routing.
D
Distractor review
It forces the interface IP address to become the router ID.
This is wrong because passive-interface does not determine router-ID selection.
E
Distractor review
It disables OSPF on every interface in the router automatically.
This is wrong because passive affects the specified interface, not every interface automatically.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is assuming that configuring an interface as passive disables OSPF routing on that interface or converts OSPF routes into static routes. Candidates may also mistakenly believe that passive interfaces automatically disable OSPF on all router interfaces or force the interface IP to become the router ID. These misunderstandings arise because passive interfaces stop hello packets but do not disable OSPF or affect router ID selection. Misreading this can lead to incorrect answers about OSPF behavior and network design.
Technical deep dive
How to think about this question
OSPF (Open Shortest Path First) is a link-state routing protocol that uses hello packets to discover and maintain neighbor relationships on interfaces. A passive interface in OSPF is configured to stop sending hello packets, which prevents the formation of OSPF adjacencies on that interface. Despite this, the router continues to advertise the connected network associated with the passive interface into the OSPF domain, allowing other routers to learn about that network without forming a neighbor relationship on that link. The decision to configure an interface as passive is based on the need to reduce unnecessary OSPF traffic and improve security. Passive interfaces are typically used on interfaces connected to end hosts or stub networks where no OSPF neighbors should exist. This configuration ensures that OSPF hello packets are suppressed, preventing neighbor formation, but the network on that interface is still included in OSPF routing updates, maintaining proper route advertisement. A common exam trap is misunderstanding the effect of passive interfaces as disabling OSPF entirely on that interface or converting OSPF routes into static routes. In reality, passive interfaces only suppress hello packets and neighbor formation; they do not disable OSPF routing or affect router ID selection. This distinction is critical for correctly answering questions about OSPF passive interfaces and for designing efficient OSPF networks in practice.
KKey Concepts to Remember
- OSPF passive interfaces prevent the router from sending hello packets on that interface, stopping neighbor adjacency formation.
- Configuring an interface as passive does not stop the router from advertising the connected network into OSPF routing updates.
- Passive interfaces are typically used on links to end hosts or stub networks where no OSPF neighbors should form.
- OSPF hello packets are essential for neighbor discovery, and suppressing them on passive interfaces reduces unnecessary routing traffic.
- Passive interface configuration does not disable OSPF on the router or convert OSPF routes into static routes.
- The router ID selection process in OSPF is independent of passive interface settings and is not affected by them.
- Using passive interfaces improves network security by limiting OSPF adjacency formation to intended interfaces only.
- Passive interfaces help optimize OSPF operation by reducing routing protocol chatter on interfaces without neighbors.
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 passive interfaces prevent the router from sending hello packets on that interface, stopping neighbor adjacency formation.
What is the correct answer to this question?
The correct answer is: It suppresses OSPF hello packets on that interface. — A passive interface stops the router from sending OSPF hello packets on that interface, which means the router will not try to form neighbors there. In practical terms, this is useful on user-facing or stub-like links where no OSPF neighbor should exist. However, passive does not necessarily mean the connected network disappears from OSPF. The network can still be advertised through the router’s other active adjacencies. This is a common design and security practice because it reduces unnecessary routing chatter on interfaces that should not form adjacencies in the first place.
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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