The answer is a DNS amplification attack. This is the correct choice because the attack leverages open DNS resolvers to send large response packets to a spoofed victim IP, and the random subdomains are specifically crafted to bypass caching and force the resolver to query authoritative servers, generating maximum response size. On the Certified Ethical Hacker CEH exam, this scenario tests your ability to distinguish amplification attacks from other DDoS variants like NTP or Smurf attacks; a common trap is confusing the internal host’s outbound queries with the victim’s traffic, but remember the internal host here is acting as a reflector, not the target. For a memory tip, think “random subdomains + large responses = DNS amplification,” and recall that the attacker spoofs the victim’s IP to make the resolver send the oversized reply to the victim, not the attacker.
CEH Practice Question: Malware, Social Engineering and Network Attacks
This CEH practice question tests your understanding of malware, social engineering and network attacks. 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.
An IDS alerts on a large number of outbound DNS queries from an internal host to a suspicious domain. The queries have random subdomains and the response size is large. Which attack is MOST likely in progress?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
DNS amplification attack
A DNS amplification attack uses open DNS resolvers to send large responses to a spoofed victim IP. The random subdomains are used to generate large responses, and the outbound queries are from the internal host acting as reflector.
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.
✗
Slowloris attack
Why it's wrong here
Slowloris is an application-layer DDoS attack that holds connections open, not DNS-based.
✗
UDP flood
Why it's wrong here
UDP flood sends many UDP packets to random ports, not specifically DNS.
✓
DNS amplification attack
Why this is correct
Correct. The large responses and random subdomains indicate an amplification attack.
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.
✗
DNS tunneling
Why it's wrong here
DNS tunneling encodes data in DNS queries, but the large response size suggests amplification.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 CEH 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Malware, Social Engineering and Network Attacks — This question tests Malware, Social Engineering and Network Attacks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: DNS amplification attack — A DNS amplification attack uses open DNS resolvers to send large responses to a spoofed victim IP. The random subdomains are used to generate large responses, and the outbound queries are from the internal host acting as reflector.
What should I do if I get this CEH question wrong?
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which THREE of the following are characteristics of a DNS amplification DDoS attack? (Select three.)
hard
✓ A.Spoofs the source IP address of the victim
✓ B.Amplifies traffic by sending small queries that generate large responses
✓ C.Uses open DNS resolvers
D.Exploits the TCP handshake process
E.Floods the target with small ICMP packets
Why A: DNS amplification uses open DNS resolvers, spoofs the victim's IP, and exploits small queries to generate large responses, thereby amplifying traffic.
Variation 2. Which TWO of the following are characteristics of a DNS amplification attack? (Select 2)
medium
A.It targets the victim's MAC address
✓ B.It uses spoofed source IP addresses
✓ C.It exploits open DNS resolvers
D.It requires the attacker to be on the same subnet as the victim
E.It uses ICMP echo requests
Why B: DNS amplification uses open resolvers and spoofed source IPs to send small queries that yield large responses, amplifying traffic.
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 CEH practice question is part of Courseiva's free EC-Council 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 CEH 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.