Quick Answer
The answer is implementing DNSSEC. This is the most effective measure to prevent DNS spoofing because DNSSEC, or Domain Name System Security Extensions, adds cryptographic digital signatures to DNS data, allowing resolvers to verify that the response came from the authoritative source and was not tampered with during transit. Without these signatures, an attacker can easily poison a DNS cache by injecting forged records, redirecting users to malicious sites. On the Certified Ethical Hacker CEH exam, this concept tests your understanding of network security controls and often appears in questions contrasting DNSSEC with simpler defenses like port randomization or disabling recursion, which are less robust. A common trap is assuming encryption alone (like DNS over HTTPS) prevents spoofing, but DNSSEC specifically validates data integrity and origin. For a memory tip, think of DNSSEC as a "digital seal" on every DNS response—if the seal is broken or missing, the data is untrustworthy.
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 organization wants to protect against DNS spoofing attacks. Which security measure is MOST effective in preventing an attacker from poisoning DNS cache entries?
Use IPsec
Why wrong: IPsec secures IP communications, not specifically DNS.
Implement DNSSEC
DNSSEC validates DNS responses.
Use a firewall
Why wrong: Firewalls do not validate DNS data.
Disable DNS recursion
Why wrong: Disabling recursion prevents some spoofing but is not comprehensive.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Implement DNSSEC
DNSSEC adds cryptographic signatures to DNS data, preventing spoofed responses.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Use IPsec
Implement DNSSEC
Use a firewall
Why it's wrong here
Firewalls do not validate DNS data.
Disable DNS recursion
Why it's wrong here
Disabling recursion prevents some spoofing but is not comprehensive.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CEH NAT questions on configuration and troubleshooting.
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FAQ
Malware, Social Engineering and Network Attacks — This question tests Malware, Social Engineering and Network Attacks — Static NAT maps one inside address to one outside address..
The correct answer is: Implement DNSSEC — DNSSEC adds cryptographic signatures to DNS data, preventing spoofed responses.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CEH NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 21, 2026
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.
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