350-601 Security Practice Question
A server team reports that after connecting a new server to a switchport, the server can receive traffic but cannot send traffic. The port is configured with port security. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the distinction between the three port security violation modes (protect, restrict, shutdown) by presenting a symptom of one-way traffic, which candidates mistakenly attribute to a shutdown or restrict mode rather than the silent dropping behavior of protect.
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 port security violation mode is set to protect
When port security violation mode is set to 'protect', the switch drops traffic from unauthorized MAC addresses without generating a syslog message or incrementing the violation counter. In this scenario, the server can receive traffic because the switch still forwards broadcast and unknown unicast frames to the port, but the server's transmitted frames are silently dropped because the switch does not learn the server's MAC address or forward its frames. This matches the symptom of one-way communication where the server can receive but not send.
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 port is in errdisable state
Why it's wrong here
In errdisable, no traffic is received or sent.
- ✓
The port security violation mode is set to protect
Why this is correct
Protect mode drops offending frames silently, allowing the server to receive but not send traffic from an unknown MAC.
- ✗
The port security maximum is set to 1 and another device is connected
Why it's wrong here
That would cause a violation, but the behavior depends on mode.
- ✗
The server MAC address is not in the allowed list
Why it's wrong here
If the MAC is not allowed, the violation mode determines action; protect mode would drop as described.
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 |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-601 exam.