ISC2 CC Network Security Practice Question
A security analyst at a mid-sized company is reviewing network traffic logs and notices that an internal host is repeatedly sending TCP SYN packets to many different external IP addresses on port 443, but never completing the three-way handshake. The analyst suspects a malware infection. Which type of attack is most likely occurring?
⚠ Common exam trap
The trap here is assuming that any flood of packets is a ping flood or Smurf attack, but the key differentiator is the protocol and handshake behavior.
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
✓
SYN flood
The host is sending numerous TCP SYN packets to various external IP addresses on port 443 without completing the three-way handshake. This pattern indicates a SYN flood attack, where the attacker attempts to exhaust connection resources on targets. The host is likely part of a botnet. The other options describe different attack types that do not match the observed traffic 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.
- ✗
MAC flooding
Why it's wrong here
MAC flooding is an attack that overwhelms a switch's MAC address table by sending frames with many different source MAC addresses, causing the switch to broadcast frames. This scenario involves IP packets to external addresses, not MAC address table manipulation. The behavior described is not consistent with MAC flooding.
- ✓
SYN flood
Why this is correct
A SYN flood is a type of denial-of-service attack where the attacker sends a large number of TCP SYN packets to a target but does not complete the handshake, exhausting the target's connection resources. In this scenario, the internal host is sending SYN packets to many external IPs on port 443 without completing the handshake, which is characteristic of a SYN flood. The host is likely compromised and participating in a botnet.
- ✗
Smurf attack
Why it's wrong here
A Smurf attack involves sending ICMP echo requests to a broadcast address with a spoofed source IP, causing many hosts to reply to the victim. This scenario involves TCP SYN packets to port 443, not ICMP, and the host is sending to many external IPs, not to a broadcast address. Therefore, it is not a Smurf attack.
- ✗
Ping flood
Why it's wrong here
A ping flood is a denial-of-service attack that overwhelms a target with ICMP echo requests. The scenario describes TCP SYN packets on port 443, not ICMP traffic. Additionally, the traffic is directed to many external IPs, not a single target, so it does not match the pattern of a ping flood.
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Related to this question
Learn chapter
Secure Network Architecture and Design
Key term
Denial-of-service
A Denial-of-service (DoS) attack is an attempt to make a computer, network, or online service unavailable to its intended users by overwhelming it with fake traffic or requests.
Key term
TCP
TCP is a connection-oriented transport layer protocol that ensures reliable, ordered, and error-checked delivery of data between applications over IP networks.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This CC practice question is part of Courseiva's free ISC2 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 CC exam.