200-201 Security Monitoring Practice Question
A security analyst is reviewing firewall logs and notices a rule that denies traffic from source IP 10.0.0.5 to destination port 3389. What service is being blocked?
⚠ Common exam trap
Cisco often tests the association of default port numbers with common services, and the trap here is that candidates may confuse RDP (3389) with SSH (22) or SMTP (25) due to similar remote access or management functions.
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
✓
RDP
Port 3389 is the default port for Remote Desktop Protocol (RDP), which is used for remote graphical desktop access to Windows systems. The firewall rule denying traffic from 10.0.0.5 to this port blocks RDP connections, preventing that host from initiating remote desktop sessions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
RDP
Why this is correct
Port 3389 is the registered TCP port for Remote Desktop Protocol, so a deny rule targeting it blocks RDP sessions. The stem's constraint — destination port 3389 — maps directly to RDP, Microsoft's protocol for remote graphical access to Windows hosts. No other listed service uses this port.
- ✗
SNMP
Why it's wrong here
SNMP uses UDP ports 161 and 162, so a rule denying port 3389 does not block it. SNMP is the correct answer when the denied port is 161 or 162, as when investigating network management polling failures.
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SMTP
Why it's wrong here
SMTP uses TCP port 25, so denying port 3389 does not block mail relay. SMTP is the correct answer when the denied port is 25, as when troubleshooting blocked outbound email from an internal host.
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SSH
Why it's wrong here
SSH uses TCP port 22, so denying port 3389 does not block remote shell access. SSH is the correct answer when the denied port is 22, as when investigating blocked administrative access to a Linux server.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-201 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 200-201 exam.