The answer is a large number of incomplete TCP connections, specifically SYN packets without corresponding ACKs, and a sudden increase in traffic from a single source IP address. These are common indicators of a denial-of-service (DoS) attack because the first reflects a classic SYN flood, where the attacker initiates the TCP handshake but never completes it, exhausting the target’s connection queue. The second reveals a direct DoS, where a single compromised host overwhelms the victim with a traffic spike, unlike a distributed attack that uses multiple sources. On the Cisco CyberOps Associate 200-201 exam, this tests your ability to distinguish DoS from DDoS and recognize anomalous traffic patterns in network monitoring logs. A common trap is confusing a high volume of legitimate traffic with an attack, so focus on the incompleteness of connections or the singularity of the source. Memory tip: think “SYN without ACK” as a half-open door, and “one IP flood” as a single firehose.
200-201 Security Concepts Practice Question
This 200-201 practice question tests your understanding of security concepts. 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.
Which TWO of the following are common indicators of a denial-of-service (DoS) attack?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A sudden increase in traffic from a single source IP address
Option D is correct because a sudden increase in traffic from a single source IP address is a classic indicator of a direct DoS attack, where the attacker uses a single compromised host to flood the target with packets, overwhelming its resources. This contrasts with a distributed denial-of-service (DDoS) attack, which uses multiple sources. The abrupt spike in volume from one IP is a clear anomaly that network monitoring tools flag as a potential DoS event.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
A low level of network utilization on the target server
Why it's wrong here
DoS attacks increase utilization, not decrease.
✗
A gradual increase in traffic from multiple geographic locations
Why it's wrong here
This may be normal traffic growth or a marketing campaign.
✗
A high number of DNS queries from diverse source IPs
Why it's wrong here
This could be a DDoS, but the question asks for DoS (single source).
✓
A sudden increase in traffic from a single source IP address
Why this is correct
This indicates a potential DoS attack from that IP.
Related concept
Read the scenario before looking for a memorised answer.
✓
A large number of incomplete TCP connections (SYN packets without ACK)
Why this is correct
This is characteristic of a SYN flood DoS attack.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between a single-source DoS attack (option D) and a distributed DDoS attack (options B and C), where candidates may confuse the gradual increase from multiple locations as a DoS indicator instead of recognizing it as a DDoS characteristic.
Detailed technical explanation
How to think about this question
A SYN flood attack, which corresponds to option E, exploits the TCP three-way handshake by sending a high volume of SYN packets without completing the handshake (no ACK), exhausting the server's connection table (backlog queue) and preventing legitimate connections. In a real-world scenario, a single-source SYN flood can be mitigated by rate-limiting or blackholing the offending IP, while a distributed SYN flood requires more advanced defenses like SYN cookies or dedicated DDoS mitigation services.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A sudden increase in traffic from a single source IP address — Option D is correct because a sudden increase in traffic from a single source IP address is a classic indicator of a direct DoS attack, where the attacker uses a single compromised host to flood the target with packets, overwhelming its resources. This contrasts with a distributed denial-of-service (DDoS) attack, which uses multiple sources. The abrupt spike in volume from one IP is a clear anomaly that network monitoring tools flag as a potential DoS event.
What should I do if I get this 200-201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.