Quick Answer
The answer is a SYN flood attack. This is correct because a SYN flood exploits the TCP three-way handshake by sending a massive volume of SYN packets to multiple hosts, never completing the handshake with the final ACK, which exhausts server resources and denies service to legitimate traffic. The alert’s description of a spike in TCP SYN packets from a single external IP to multiple internal hosts on port 443 directly matches this behavior, targeting HTTPS services. On the Cisco CyberOps Associate 200-201 exam, this scenario tests your ability to distinguish a SYN flood from other attacks like a ping flood or port scan, which lack the specific SYN-only pattern to multiple destinations. A common trap is confusing it with a SYN scan, but a scan probes for open ports, whereas a flood aims to overwhelm resources. Memory tip: think “SYN only, never ACK” — if the handshake never finishes, it’s a flood.
This 200-201 practice question tests your understanding of network intrusion analysis. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A security analyst reviews an alert from the IPS that shows a spike in TCP SYN packets from an external IP to multiple internal hosts on port 443. What is the most likely attack type?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
SYN flood
A SYN flood sends many TCP SYN packets to exhaust resources.
Port scanning
Why wrong: Port scanning typically targets multiple ports on a single host, not multiple hosts on a single port.
Man-in-the-middle
Why wrong: MITM intercepts communications between two parties.
DNS amplification
Why wrong: DNS amplification uses UDP, not TCP SYN.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
SYN flood
A SYN flood attack exploits the TCP three-way handshake by sending a high volume of SYN packets to multiple hosts without completing the handshake, exhausting server resources. The alert describes a spike in TCP SYN packets from an external IP to multiple internal hosts on port 443, which matches the behavior of a distributed SYN flood targeting HTTPS services. This is the most likely attack because the IPS is detecting the initial connection attempts characteristic of a SYN flood.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
SYN flood
Why this is correct
A SYN flood sends many TCP SYN packets to exhaust resources.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Port scanning
Why it's wrong here
Port scanning typically targets multiple ports on a single host, not multiple hosts on a single port.
Man-in-the-middle
Why it's wrong here
MITM intercepts communications between two parties.
DNS amplification
Common exam traps
Cisco often tests the distinction between a SYN flood and port scanning by emphasizing that a SYN flood targets multiple hosts on the same port, while port scanning targets multiple ports on a single host.
Detailed technical explanation
In a SYN flood, the attacker sends a barrage of SYN packets with spoofed source IP addresses, causing the target to allocate memory for half-open connections in the SYN backlog queue. Modern operating systems mitigate this with SYN cookies, which encode connection state in the SYN-ACK sequence number, but high-volume floods can still overwhelm network throughput. Real-world SYN floods often target web servers on port 443 to disrupt HTTPS services, as seen in DDoS campaigns like Mirai.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 200-201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Network Intrusion Analysis — This question tests Network Intrusion Analysis — Read the scenario before looking for a memorised answer..
The correct answer is: SYN flood — A SYN flood attack exploits the TCP three-way handshake by sending a high volume of SYN packets to multiple hosts without completing the handshake, exhausting server resources. The alert describes a spike in TCP SYN packets from an external IP to multiple internal hosts on port 443, which matches the behavior of a distributed SYN flood targeting HTTPS services. This is the most likely attack because the IPS is detecting the initial connection attempts characteristic of a SYN flood.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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