The answer is a sudden increase in ICMP echo request packets from many IPs, alongside spikes in UDP traffic to a single target and a flood of SYN packets with no corresponding ACKs. These three patterns are classic network layer DDoS attack indicators because they exploit stateless or connectionless protocols at Layer 3/4 to overwhelm bandwidth or processing capacity. A UDP flood, for example, bombards random ports with high-volume packets, bypassing any handshake requirement, while a SYN flood leverages the TCP three-way handshake by leaving half-open connections. On the Cisco SCOR / CCNP Security Core 350-701 exam, this question tests your ability to distinguish network-layer floods from application-layer attacks; a common trap is confusing a slow HTTP POST flood with these volumetric patterns. Remember the memory tip: “UDP, SYN, ICMP—if it’s raw and handshake-free, it’s Layer 3/4 DDoS for me.”
350-701 Security Concepts Practice Question
This 350-701 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 THREE of the following are common indicators of a DDoS attack at the network layer?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A spike in UDP traffic to a single target
A spike in UDP traffic to a single target is a classic indicator of a UDP flood attack, a common network-layer DDoS. Attackers send a high volume of UDP packets, often to random ports, overwhelming the target's ability to process them and consuming bandwidth. This is a direct Layer 3/4 attack that does not require a completed handshake, making it easy to generate and hard to mitigate without proper filtering.
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.
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 network-layer (Layer 3/4) and application-layer (Layer 7) indicators, so candidates mistakenly choose 'unusual traffic on non-standard ports' as a network-layer indicator when it is actually a sign of application-layer attacks like HTTP floods or DNS amplification.
Detailed technical explanation
How to think about this question
Network-layer DDoS attacks exploit the stateless nature of IP and ICMP, allowing attackers to spoof source addresses easily. For example, a UDP flood can saturate a link's bandwidth, while a SYN flood exploits the TCP three-way handshake by sending many SYN packets without completing the handshake, exhausting the target's connection table (backlog queue). Real-world mitigation often involves rate-limiting, ACLs, or specialized DDoS scrubbing centers that filter traffic based on volumetric thresholds.
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 350-701 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 spike in UDP traffic to a single target — A spike in UDP traffic to a single target is a classic indicator of a UDP flood attack, a common network-layer DDoS. Attackers send a high volume of UDP packets, often to random ports, overwhelming the target's ability to process them and consuming bandwidth. This is a direct Layer 3/4 attack that does not require a completed handshake, making it easy to generate and hard to mitigate without proper filtering.
What should I do if I get this 350-701 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.
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Question Discussion
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