The correct answer is to configure `ip ospf hello-interval 10` and `ip ospf dead-interval 40` under R1’s GigabitEthernet0/0, set the network type to broadcast, apply `passive-interface GigabitEthernet0/1` under router ospf 1 on R1, and set R2’s router-id to 2.2.2.2. This resolves the OSPF timer mismatch because OSPF requires matching hello and dead intervals between neighbors to form an adjacency; R1’s non-default timers (30/120) and non-broadcast network type prevented synchronization with R2’s defaults (10/40 and broadcast). On the CCNA 200-301 v2 exam, this scenario tests your ability to troubleshoot OSPF neighbor formation by verifying interface-level parameters and understanding that `passive-interface` suppresses hellos on a specific interface without affecting others—a common trap is applying it globally, which would block all OSPF hellos. Remember the memory tip: “Timers must match, passive is per-interface, and broadcast is the default on Ethernet.”
CCNA IP Routing Practice Question
This 200-301 practice question tests your understanding of ip routing. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Network Topology
You are connected to R1 via console. R1 and R2 are directly connected via GigabitEthernet0/0. Configure OSPF process 1 on both routers so that they form a full adjacency. R1's router-id must be 1.1.1.1, and R2's router-id must be 2.2.2.2. Use network statements to advertise the direct link. Ensure that R1 does not send OSPF hellos out of its GigabitEthernet0/1 interface. The current configuration on R1 has mismatched hello and dead timers, and an incorrect network type, preventing adjacency. Fix all issues.
R1# show running-config | section router ospf
router ospf 1
router-id 1.1.1.1
network 192.0.2.0 0.0.0.3 area 0
network 10.0.0.0 0.255.255.255 area 0
passive-interface GigabitEthernet0/1
!
R1# show ip ospf interface gigabitethernet 0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 192.0.2.1/30, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 1.1.1.1, Interface address 192.0.2.1
No backup designated router on this network
Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
oob-resync timeout 120
Hello due in 00:00:18
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
R1# show ip ospf neighbor
R1#
R2# show running-config | section router ospf
router ospf 1
router-id 2.2.2.2
network 192.0.2.0 0.0.0.3 area 0
!
R2# show ip ospf interface gigabitethernet 0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 192.0.2.2/30, Area 0
Process ID 1, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 1.1.1.1, Interface address 192.0.2.1
Backup Designated Router (ID) 2.2.2.2, Interface address 192.0.2.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:03
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 1.1.1.1 (Designated Router)
Suppress hello for 0 neighbor(s)
A
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.
This option correctly fixes the timer mismatch by setting hello to 10 and dead to 40 on R1's GigabitEthernet0/0, matching R2's defaults. It also sets the router-id on R2 and uses passive-interface on R1's GigabitEthernet0/1 to prevent sending hellos, as required. The network type is already broadcast by default, so no change is needed.
B
On R1, configure 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120' under interface GigabitEthernet0/0, and set network type to point-to-point. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface default' under router ospf 1.
Why wrong: This is incorrect because setting hello to 30 and dead to 120 on R1 does not match R2's default timers (10 and 40), so adjacency would still fail. Also, changing network type to point-to-point is unnecessary and would not fix the timer mismatch. Using 'passive-interface default' would suppress hellos on all interfaces, including the one needed for adjacency.
C
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and set network type to point-to-point. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.
Why wrong: This is incorrect because changing the network type to point-to-point is unnecessary and could cause issues if the actual link is broadcast (e.g., Ethernet). The default broadcast network type works fine for Ethernet links. The timer fix and passive-interface are correct, but the network type change is not required and may break adjacency if R2 remains broadcast.
D
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'network 10.0.0.0 0.255.255.255 area 0' under router ospf 1.
Why wrong: This is incorrect because adding a network statement for 10.0.0.0/8 is unnecessary and could advertise additional interfaces if they exist. The direct link should be advertised via a network statement that matches the link address, not a broad range. The timer fix and router-id are correct, but the network statement is not required if the interface is already in OSPF via a more specific statement.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.
The adjacency was failing because R1 had incorrect hello (30) and dead (120) timers, while R2 used defaults (10/40). Additionally, R1’s network type was set to a non-broadcast type, causing a mismatch. To fix, on R1’s GigabitEthernet0/0, set hello-interval 10, dead-interval 40, and network type broadcast. In OSPF process 1 on R1, configure passive-interface GigabitEthernet0/1 to suppress hellos on that interface. On R2, under router ospf 1, set router-id 2.2.2.2. Option A addresses all requirements. Option B uses wrong timers and passive-interface default, which blocks hellos on all interfaces, breaking adjacency. Option C sets network type point-to-point, creating a type mismatch with R2’s broadcast, preventing adjacency. Option D omits the passive-interface command, failing to suppress hellos on GigabitEthernet0/1 as required.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.
Why this is correct
This option correctly fixes the timer mismatch by setting hello to 10 and dead to 40 on R1's GigabitEthernet0/0, matching R2's defaults. It also sets the router-id on R2 and uses passive-interface on R1's GigabitEthernet0/1 to prevent sending hellos, as required. The network type is already broadcast by default, so no change is needed.
On R1, configure 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120' under interface GigabitEthernet0/0, and set network type to point-to-point. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface default' under router ospf 1.
Why it's wrong here
This is incorrect because setting hello to 30 and dead to 120 on R1 does not match R2's default timers (10 and 40), so adjacency would still fail. Also, changing network type to point-to-point is unnecessary and would not fix the timer mismatch. Using 'passive-interface default' would suppress hellos on all interfaces, including the one needed for adjacency.
✗
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and set network type to point-to-point. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.
Why it's wrong here
This is incorrect because changing the network type to point-to-point is unnecessary and could cause issues if the actual link is broadcast (e.g., Ethernet). The default broadcast network type works fine for Ethernet links. The timer fix and passive-interface are correct, but the network type change is not required and may break adjacency if R2 remains broadcast.
✗
On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'network 10.0.0.0 0.255.255.255 area 0' under router ospf 1.
Why it's wrong here
This is incorrect because adding a network statement for 10.0.0.0/8 is unnecessary and could advertise additional interfaces if they exist. The direct link should be advertised via a network statement that matches the link address, not a broad range. The timer fix and router-id are correct, but the network statement is not required if the interface is already in OSPF via a more specific statement.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.Correct answer▾
Why this is correct
This option correctly fixes the timer mismatch by setting hello to 10 and dead to 40 on R1's GigabitEthernet0/0, matching R2's defaults. It also sets the router-id on R2 and uses passive-interface on R1's GigabitEthernet0/1 to prevent sending hellos, as required. The network type is already broadcast by default, so no change is needed.
✗On R1, configure 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120' under interface GigabitEthernet0/0, and set network type to point-to-point. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface default' under router ospf 1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that OSPF requires matching hello and dead timers for adjacency; setting them to non-default values without matching the neighbor prevents adjacency. Additionally, 'passive-interface default' would make all interfaces passive, which is not the requirement.
Why candidates choose this
Candidates might think that since R1 had mismatched timers, they should keep those values and adjust R2 instead, or they might confuse the default timers with the existing mismatched ones.
✗On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and set network type to point-to-point. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that OSPF network types must match on both ends; changing only one side to point-to-point would cause a mismatch, preventing adjacency. The default broadcast type is appropriate for Ethernet.
Why candidates choose this
Candidates might think that point-to-point is more efficient or that it avoids DR/BDR elections, but for a simple direct link, broadcast works fine and is the default. They may also confuse the requirement to fix the network type with the timer issue.
✗On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'network 10.0.0.0 0.255.255.255 area 0' under router ospf 1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the network statement should be precise to avoid unintended advertisements. The existing configuration already had an extra network statement (10.0.0.0/8) that was unnecessary but not harmful; adding it again is redundant and not the correct fix.
Why candidates choose this
Candidates might think that adding a network statement is necessary to advertise the link, but the question states to use network statements to advertise the direct link, implying a specific statement is already in place or should be configured. They may also confuse the requirement with the need to include all interfaces.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
IP Routing — This question tests IP Routing — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: On R1, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0, and ensure network type is broadcast. On R2, configure 'router-id 2.2.2.2' under router ospf 1. Also, on R1, add 'passive-interface GigabitEthernet0/1' under router ospf 1. — The adjacency was failing because R1 had incorrect hello (30) and dead (120) timers, while R2 used defaults (10/40). Additionally, R1’s network type was set to a non-broadcast type, causing a mismatch. To fix, on R1’s GigabitEthernet0/0, set hello-interval 10, dead-interval 40, and network type broadcast. In OSPF process 1 on R1, configure passive-interface GigabitEthernet0/1 to suppress hellos on that interface. On R2, under router ospf 1, set router-id 2.2.2.2. Option A addresses all requirements. Option B uses wrong timers and passive-interface default, which blocks hellos on all interfaces, breaking adjacency. Option C sets network type point-to-point, creating a type mismatch with R2’s broadcast, preventing adjacency. Option D omits the passive-interface command, failing to suppress hellos on GigabitEthernet0/1 as required.
What should I do if I get this 200-301 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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