350-601 Network Practice Question
A data center design requires Layer 2 extension between two sites using OTV. The network engineer notices that MAC addresses from Site A are not learned at Site B. OTV adjacency is up, and both sites have the same overlay interface configured. Which configuration issue is most likely the cause?
⚠ Common exam trap
Cisco often tests the distinction between control-plane (adjacency) and data-plane (VLAN transport) issues, and the trap here is that candidates assume a working OTV adjacency guarantees all VLANs are extended, overlooking the need to explicitly allow the site VLAN on the join interface.
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 site VLAN is not allowed on the OTV join interface.
D is correct because the OTV join interface must have the site VLAN allowed; if the site VLAN is not permitted on the join interface, the OTV edge device cannot send or receive encapsulated traffic for that VLAN, preventing MAC address learning between sites even though the OTV adjacency is up.
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 OTV control group is misconfigured on one side.
Why it's wrong here
Control group misconfiguration would affect adjacency, not MAC learning.
- ✗
The spanning tree root bridge is different at each site.
Why it's wrong here
OTV encapsulates STP BPDUs; different root bridges do not prevent MAC learning.
- ✗
The multicast group range for the overlay does not match.
Why it's wrong here
Multicast group range is for data traffic; mismatch would cause forwarding issues but not prevent MAC learning if adjacency is up.
- ✓
The site VLAN is not allowed on the OTV join interface.
Why this is correct
The join interface must be a trunk that carries the site VLAN for OTV to forward traffic.
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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