ISC2 CC Network Security Practice Question
A security analyst is investigating a potential DDoS attack. Which of the following are common indicators of a DDoS? (Choose TWO)
⚠ Common exam trap
Test-takers frequently confuse DoS (single source) with DDoS (many sources) and assuming resource usage always drops during an attack, when in fact CPU and bandwidth typically spike.
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
✓
Unusually high traffic volume from multiple IP addresses
Option B is correct because a DDoS (Distributed Denial-of-Service) attack by definition originates from many compromised hosts (a botnet), so the analyst would observe an unusually high volume of traffic arriving from numerous, often geographically dispersed IP addresses. Option D is correct because the flood of requests exhausts server, bandwidth, or connection-table resources, which manifests as slow network performance, increased latency, timeouts, and unresponsive services for legitimate users. Option A is wrong because a DDoS typically drives CPU, memory, and bandwidth utilization up, not down. Option C is wrong because traffic from a single source describes a DoS attack, not a distributed one. Option E is wrong because DNS query volume usually spikes during many DDoS attacks (e.g., DNS amplification/reflection) rather than decreasing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Low CPU usage on servers
Why it's wrong here
Sustained attack traffic drives CPU, memory and connection-table usage upward, so low CPU contradicts a DDoS. Low utilisation would be the expected finding when validating that a suspected spike was benign, or when sizing capacity after an attack subsides.
- ✓
Unusually high traffic volume from multiple IP addresses
Why this is correct
Unusually high traffic volume from multiple IP addresses directly satisfies the distributed-source constraint distinguishing DDoS from single-origin DoS. Attackers coordinate botnets so requests flood from many geographically dispersed hosts, exhausting bandwidth or connection tables. This pattern is a primary detection indicator in Microsoft Entra ID and network monitoring tools.
- ✗
Single source sending many packets
Why it's wrong here
A single source sending many packets describes a DoS from one host, not a distributed attack. This pattern is the correct indicator when investigating a single compromised machine flooding a target, where blocking one IP remediates the incident.
- ✓
Slow network performance and increased latency
Why this is correct
Flooded links saturate bandwidth and queue packets, so round-trip times climb and throughput collapses — the direct symptom of volumetric or application-layer flooding. Slow performance and rising latency satisfy the stem's demand for common DDoS indicators, distinguishing traffic deluge from a single compromised host or malware infection.
- ✗
Decrease in DNS queries
Why it's wrong here
DDoS floods typically increase DNS query volume through amplification and botnet resolution, so a decrease points elsewhere. Falling DNS queries fit a resolver outage or misconfigured forwarder scenario, where clients cannot reach name servers at all.
Visual reference
Go deeper
Related to this question
Learn chapter
Network Security Foundations
Key term
Distributed Denial-of-service
A cyberattack where many compromised computers flood a target system with traffic, making it unavailable to legitimate users.
Key term
DoS
A cyberattack that floods a target with traffic or requests to exhaust its resources, making it unavailable to legitimate users.
About these practice questions
One of 989 original CC practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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.