mediumMultiple Choice
350-401 Practice Question: Examine the following configuration: interface…
Examine the following configuration:
interface GigabitEthernet0/0 ip address 172.16.1.1 255.255.255.0
ipv6 address 2001:db8:1::1/64 ipv6 ospf 100 area 0 !
What is missing from this configuration to enable OSPFv3 on this interface?
⚠ Common exam trap
Cisco often tests the requirement that an OSPFv3 process must be created globally with 'ipv6 router ospf <process-id>' before interface-level OSPFv3 commands will work, leading candidates to mistakenly think the interface configuration alone is sufficient.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The command 'ipv6 router ospf 100' must be added globally to create the OSPFv3 process.
OSPFv3 requires an active OSPFv3 process on the router before it can be enabled on any interface. The 'ipv6 router ospf 100' global command creates the OSPFv3 process with process ID 100, which is necessary for the interface-level 'ipv6 ospf 100 area 0' command to function. Without this global process, the interface configuration is incomplete and OSPFv3 will not operate.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The configuration is complete; no additional commands are needed.
Why it's wrong here
This answer assumes the interface-level OSPFv3 settings alone are sufficient, but a router cannot participate in OSPFv3 without an active routing process. Commands such as 'ipv6 ospf 100 area 0' are only accepted on an interface once the global router process 'ipv6 router ospf 100' exists. Without that process, the configuration is not complete and no OSPFv3 adjacency will form.
- ✓
The command 'ipv6 router ospf 100' must be added globally to create the OSPFv3 process.
Why this is correct
The global command 'ipv6 router ospf 100' creates the OSPFv3 routing process with process ID 100 and enters router configuration mode. Only after this process exists can interface-level commands like 'ipv6 ospf 100 area 0' become operational. This is the missing required step, making the configuration functional and allowing the router to exchange LSAs with its neighbors.
- ✗
The interface needs the 'ipv6 ospf network point-to-point' command to work.
Why it's wrong here
The 'ipv6 ospf network point-to-point' command changes the OSPFv3 network type for an interface, which is an optional tuning action. OSPFv3 defaults to broadcast network type on Ethernet interfaces, causing DR/BDR election, but the protocol still works without changing it. The command is irrelevant to the fundamental requirement of first creating the global OSPFv3 process, so its absence does not prevent OSPFv3 from running.
- ✗
The 'ipv6 unicast-routing' command must be enabled globally.
Why it's wrong here
Although routing IPv6 traffic end-to-end requires 'ipv6 unicast-routing' to actually forward packets, the OSPFv3 routing protocol itself can operate independently of this global switch. On many modern IOS versions, IPv6 unicast routing is enabled by default, and even if it were disabled, OSPFv3 could still establish adjacencies and build its LSDB. The failure described in this scenario is specifically the lack of a router process, not a missing packet-forwarding capability.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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