LPIC-2 DNS, Web and Mail Services Practice Question
This LPIC-2 practice question tests your understanding of dns, web and mail services. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company uses BIND9 as the authoritative name server for its public zone example.com. External users report that they cannot resolve the MX record for the domain, but internal users can. What is the most likely cause?
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
✓
The allow-query ACL restricts queries to the internal network.
Option B is correct because the allow-query ACL in BIND9 restricts which source IP addresses are permitted to send queries to the server. If it is set to allow only the internal network (e.g., 192.168.0.0/16), external users' queries are rejected, causing resolution failures for MX records and all other records. Internal users succeed because their IPs match the ACL, while external users receive a REFUSED response or no answer.
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.
✗
The zone file lacks an MX record.
Why it's wrong here
An absent MX record would cause failure for both internal and external users.
✓
The allow-query ACL restricts queries to the internal network.
Why this is correct
If allow-query limits to internal IPs, external queries are rejected, causing resolution failures for external users.
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.
✗
The server is behind a firewall that blocks UDP port 53.
Why it's wrong here
A firewall blocking port 53 would affect both internal and external users equally.
✗
The recursion is set to no.
Why it's wrong here
Disabling recursion is normal for authoritative servers and does not block queries; it only prevents recursive lookups.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse allow-query (which controls who can send queries) with allow-transfer (zone transfers) or recursion settings, or they assume a missing record is the cause when the symptom is selective failure based on client location.
Detailed technical explanation
How to think about this question
In BIND9, the allow-query directive can be applied globally in options {} or per zone in zone {}. When set to a restricted ACL, the server returns a REFUSED response (RCODE 5) to unauthorized clients, which is distinct from NXDOMAIN or SERVFAIL. This is a common security measure to prevent external access to internal DNS data, but it can inadvertently block legitimate external queries for public zones if misconfigured.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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.
DNS, Web and Mail Services — This question tests DNS, Web and Mail Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The allow-query ACL restricts queries to the internal network. — Option B is correct because the allow-query ACL in BIND9 restricts which source IP addresses are permitted to send queries to the server. If it is set to allow only the internal network (e.g., 192.168.0.0/16), external users' queries are rejected, causing resolution failures for MX records and all other records. Internal users succeed because their IPs match the ACL, while external users receive a REFUSED response or no answer.
What should I do if I get this LPIC-2 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
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 LPIC-2 practice question is part of Courseiva's free LPI 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 LPIC-2 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.