hardMultiple Choice
200-201 Practice Question: Refer to the exhibit
Exhibit
Refer to the exhibit. syslog: %ASA-4-106023: Deny tcp src inside:10.0.0.10/12345 dst outside:203.0.113.5/22 by access-group "OUTSIDE" [0x0, 0x0] syslog: %ASA-4-106023: Deny tcp src inside:10.0.0.10/12346 dst outside:203.0.113.5/23 by access-group "OUTSIDE" [0x0, 0x0] syslog: %ASA-4-106023: Deny tcp src inside:10.0.0.10/12347 dst outside:203.0.113.5/25 by access-group "OUTSIDE" [0x0, 0x0]
Refer to the exhibit. A firewall log shows denied TCP traffic from an internal host to an external IP on consecutive ports. What type of activity is indicated?
⚠ Common exam trap
Cisco often tests the distinction between reconnaissance (port scanning) and exploitation (worm propagation) by presenting a log of denied traffic to consecutive ports, leading candidates to confuse the scanning phase with the actual attack phase, such as worm propagation or DoS.
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
✓
Port scanning
The firewall log shows denied TCP traffic from an internal host to an external IP on consecutive ports. This sequential pattern of connection attempts to multiple ports on the same target is a classic indicator of a port scan, where an attacker probes for open ports to identify potential services to exploit. The firewall's deny action confirms the traffic was blocked, but the behavior itself is characteristic of reconnaissance activity, specifically a TCP connect scan.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Port scanning
Why this is correct
Sequential destination ports from one internal host indicate systematic probing of services to discover open listeners. A single connection would be normal traffic; consecutive denied attempts on incrementing ports is the signature of port scanning reconnaissance.
- ✗
Worm propagation
Why it's wrong here
Consecutive destination ports from one internal host suggest a port scan, reconnaissance activity, rather than worm propagation, which spreads by exploiting vulnerabilities across many hosts. Worm behaviour would show repeated exploitation attempts against multiple internal targets on a single service port.
- ✗
Denial of service
Why it's wrong here
A denial of service aims to exhaust a target's resources, producing high-volume traffic toward one destination; this log shows a single internal host probing consecutive ports on an external IP, which is reconnaissance. DoS analysis would be the right choice when traffic floods a service to degrade availability, not when ports are enumerated.
- ✗
Data exfiltration
Why it's wrong here
Exfiltration requires successful outbound transfer of data to an external destination; these connections were denied, so no data left the host. Sequential destination ports indicate scanning behaviour instead. Exfiltration detection applies when large volumes of data traverse an allowed egress path, typically identified through DLP or flow-volume analysis rather than blocked connection attempts.
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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.