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200-201 Practice Question: A security analyst for a medium-sized enterprise…

A security analyst for a medium-sized enterprise is monitoring the network using Cisco Stealthwatch. They notice a sudden spike in traffic originating from an internal host (IP 10.10.10.50) communicating with multiple external IP addresses on port 445 (SMB). The host is a Windows server that typically serves web applications on ports 80 and 443. The analyst checks the host's firewall logs and finds that Windows Firewall is disabled. The host's antivirus is up to date and no alerts were triggered. The traffic pattern shows multiple connection attempts to /24 subnets across the internet, each with a single packet per destination. Based on this behavior, what is the most likely issue?

⚠ Common exam trap

Cisco often tests the distinction between reconnaissance (scanning) and attack (exploitation/DDoS), where candidates may confuse the single-packet scanning pattern with DDoS amplification or legitimate scanning, but the key is the lack of handshake completion and the disabled firewall indicating compromise.

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 host is infected with malware that is performing network reconnaissance.

The traffic pattern—multiple connection attempts to /24 subnets across the internet, each with a single packet per destination—is classic behavior for network reconnaissance, specifically scanning for open SMB ports. The host's Windows Firewall being disabled and the lack of antivirus alerts indicate that the host is likely compromised and running malware that is performing this reconnaissance, as legitimate scanning or DDoS amplification would not exhibit this single-packet-per-destination pattern.

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 host is infected with malware that is performing network reconnaissance.

    Why this is correct

    The pattern matches malware scanning for SMB vulnerabilities (e.g., EternalBlue).

  • The host is part of a distributed vulnerability scanning initiative.

    Why it's wrong here

    No indication of authorization; also the host's typical function is web serving, not scanning.

  • The host is being used for a DDoS amplification attack.

    Why it's wrong here

    DDoS amplification uses spoofed sources and large responses; here traffic is scanning many destinations.

  • The host is legitimately scanning the internet for outdated SMB shares.

    Why it's wrong here

    Legitimate scans would be authorized and typically use more targeted ranges.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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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.