The correct answer is that OSPF will run on GigabitEthernet0/0 and form adjacencies within VRF CUSTOMER_D. This happens because the OSPF process is explicitly tied to the VRF using the `router ospf 1 vrf CUSTOMER_D` command, which restricts OSPF to only those interfaces that have been placed under the same VRF with `ip vrf forwarding CUSTOMER_D`. The network statement then matches the interface’s subnet, enabling OSPF to discover neighbors and exchange routes exclusively within that VRF, a core concept in VRF-lite deployments. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding of how VRF-aware routing isolates routing protocols per VRF, a common trap being that students forget the OSPF process must be VRF-specific or mistakenly think the network command alone suffices without the VRF binding. A solid memory tip is “VRF first, then OSPF”—always bind the interface to the VRF before configuring the OSPF process for that VRF, or the adjacency will never form.
300-410 VRF-Lite Practice Question
This 300-410 practice question tests your understanding of vrf-lite. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Given this configuration on router R2:
```
ip vrf CUSTOMER_D
rd 100:1
!
interface GigabitEthernet0/0
ip vrf forwarding CUSTOMER_D
ip address 192.168.2.1 255.255.255.0
!
router ospf 1 vrf CUSTOMER_D
network 192.168.2.0 0.0.0.255 area 0
```
What will happen when this configuration is applied?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OSPF will run on GigabitEthernet0/0 and form adjacencies within VRF CUSTOMER_D.
The OSPF process is tied to VRF CUSTOMER_D, so it only runs on interfaces that belong to that VRF. The network command matches the interface, so OSPF will form adjacencies on that interface within the VRF.
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.
✓
OSPF will run on GigabitEthernet0/0 and form adjacencies within VRF CUSTOMER_D.
Why this is correct
This is correct. The OSPF process is VRF-aware and will operate only on interfaces in that VRF.
OSPF will fail because the OSPF process must be configured globally, not under the VRF.
Why it's wrong here
Incorrect. OSPF can be configured per VRF using the 'vrf' keyword.
✗
OSPF will run on all interfaces, including those not in VRF CUSTOMER_D.
Why it's wrong here
Incorrect. The VRF keyword restricts OSPF to interfaces in that VRF.
✗
The network command is invalid because it uses a wildcard mask instead of a subnet mask.
Why it's wrong here
Incorrect. OSPF uses wildcard masks in network statements.
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.
Trap categories for this question
Keyword trap
Incorrect. OSPF can be configured per VRF using the 'vrf' keyword.
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 300-410 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 300-410 OSPF questions on adjacency and route selection.
VRF-Lite — This question tests VRF-Lite — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: OSPF will run on GigabitEthernet0/0 and form adjacencies within VRF CUSTOMER_D. — The OSPF process is tied to VRF CUSTOMER_D, so it only runs on interfaces that belong to that VRF. The network command matches the interface, so OSPF will form adjacencies on that interface within the VRF.
What should I do if I get this 300-410 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 300-410 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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