This CEH practice question tests your understanding of footprinting, reconnaissance and scanning. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A security analyst issues the command `dnsenum example.com` and receives a list of subdomains, mail servers, and name servers. What information is revealed by the presence of multiple MX records?
The domain has been compromised
Why wrong: Multiple MX records are normal.
The domain uses a single mail server with multiple aliases
Why wrong: Aliases would be CNAME, not MX.
The domain uses multiple mail servers for load balancing and failover
Multiple MX records with different priorities provide failover.
The domain is participating in a DDoS attack
Why wrong: No indication of attack.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The domain uses multiple mail servers for load balancing and failover
Multiple MX records in a DNS zone file indicate that the domain is configured with more than one mail exchange server. This setup provides redundancy and load balancing for email delivery, as defined in RFC 5321. The `dnsenum` tool enumerates these records from the DNS server, revealing the domain's email infrastructure design.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The domain has been compromised
Why it's wrong here
Multiple MX records are normal.
The domain uses a single mail server with multiple aliases
Why it's wrong here
Aliases would be CNAME, not MX.
The domain uses multiple mail servers for load balancing and failover
Why this is correct
Multiple MX records with different priorities provide failover.
Related concept
Read the scenario before looking for a memorised answer.
The domain is participating in a DDoS attack
Why it's wrong here
No indication of attack.
Common exam traps
The trap here is that candidates may confuse multiple MX records with multiple A records for a single hostname, or incorrectly assume that any multiplicity in DNS records indicates a security issue, rather than recognizing it as a standard high-availability design.
Detailed technical explanation
MX records have a priority (preference) value; lower numbers indicate higher priority. During email delivery, the sending MTA attempts delivery to the lowest-priority MX first, and if that fails, it tries the next priority. This allows administrators to designate primary and backup mail servers. `dnsenum` queries the DNS for these records and can also perform zone transfers if misconfigured, revealing the full list of subdomains and associated services.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
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FAQ
Footprinting, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
The correct answer is: The domain uses multiple mail servers for load balancing and failover — Multiple MX records in a DNS zone file indicate that the domain is configured with more than one mail exchange server. This setup provides redundancy and load balancing for email delivery, as defined in RFC 5321. The `dnsenum` tool enumerates these records from the DNS server, revealing the domain's email infrastructure design.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 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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