The answer is that OSPFv3 will use IPsec MD5 authentication for all packets in area 0, including on GigabitEthernet0/0. This is because the `area 0 authentication ipsec` command under the OSPFv3 process enables IPsec-based authentication for the entire area, and any interface configured under that area—such as GigabitEthernet0/0 with `ipv6 ospf 10 area 0`—inherits this authentication automatically. On the Cisco CCNP ENARSI 300-410 exam, this configuration tests your understanding that OSPFv3, unlike OSPFv2, relies on IPsec (AH or ESP) rather than simple MD5 keys for authentication, and that area-level authentication applies to all interfaces in that area without needing per-interface commands. A common trap is assuming you must also configure authentication under the interface, but the area command suffices. Remember: for OSPFv3, think “area-wide IPsec, not per-link plaintext.”
300-410 OSPF Troubleshooting (v2/v3) Practice Question
This 300-410 practice question tests your understanding of ospf troubleshooting (v2/v3). 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.
Consider this OSPFv3 configuration on router R2:
ipv6 router ospf 10
router-id 2.2.2.2
area 0 authentication ipsec spi 256 md5 1234567890abcdef1234567890abcdef
interface GigabitEthernet0/0
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OSPFv3 will use IPsec MD5 authentication for all packets in area 0, including on GigabitEthernet0/0.
The area authentication command under OSPFv3 enables IPsec authentication for the entire area. The interface is enabled for OSPFv3 in area 0, so it will use the area authentication. However, OSPFv3 authentication uses IPsec AH or ESP; the configuration shown is valid.
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.
✓
OSPFv3 will use IPsec MD5 authentication for all packets in area 0, including on GigabitEthernet0/0.
Why this is correct
Correct. The area authentication command applies to all interfaces in that area.
The router-id is missing, so OSPFv3 will not start.
Why it's wrong here
Incorrect. The router-id is configured as 2.2.2.2.
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 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.
OSPF Troubleshooting (v2/v3) — This question tests OSPF Troubleshooting (v2/v3) — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: OSPFv3 will use IPsec MD5 authentication for all packets in area 0, including on GigabitEthernet0/0. — The area authentication command under OSPFv3 enables IPsec authentication for the entire area. The interface is enabled for OSPFv3 in area 0, so it will use the area authentication. However, OSPFv3 authentication uses IPsec AH or ESP; the configuration shown is valid.
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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