hardMultiple ChoiceObjective-mapped
350-701 Is analyzing logs from a Cisco ASA Practice Question
A security engineer is analyzing logs from a Cisco ASA. They notice that a specific internal host is generating a high volume of outbound TCP SYN packets to multiple external IP addresses on port 443, but no SYN-ACK responses are received. What is the most likely explanation?
⚠ Common exam trap
Cisco often tests the distinction between a host being the source of an attack versus being the victim, and the trap here is that candidates may assume the host is simply making legitimate outbound connections (Option D) without recognizing that the absence of SYN-ACK responses is the key anomaly that indicates an attack rather than normal traffic.
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 a SYN flood denial-of-service attack
The host is sending a high volume of TCP SYN packets to multiple external IPs on port 443 without receiving SYN-ACK responses, which is characteristic of a SYN flood attack. In a SYN flood, the attacker (or infected host) sends many SYN packets to exhaust the target's connection table, but the lack of SYN-ACK responses indicates the targets are not completing the handshake, often because the source IP is spoofed or the targets are unresponsive. The Cisco ASA logs show outbound SYN packets with no corresponding SYN-ACKs, which aligns with the host being used as a source for a denial-of-service attack.
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 ASA is configured to block outbound HTTPS traffic
Why it's wrong here
If HTTPS were blocked, the ASA would drop the SYN packets, not allow them out.
- ✗
The host is downloading a large malware file via HTTPS
Why it's wrong here
Downloading a file would require a completed TCP handshake and data transfer.
- ✓
The host is infected with malware that is performing a SYN flood denial-of-service attack
Why this is correct
Spoofed or high-volume SYN packets without responses indicate a SYN flood attack.
- ✗
The host is establishing legitimate HTTPS connections
Why it's wrong here
Legitimate HTTPS connections would show SYN-ACK responses.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-701 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 350-701 exam.