LPIC-2 Advanced Networking Configuration Practice Question
This LPIC-2 practice question tests your understanding of advanced networking configuration. 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 Linux server is configured as a DNS resolver with BIND. Users report that they cannot resolve external hostnames. The server can resolve internal names. Which of the following 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 firewall is blocking UDP port 53 outgoing from the server.
The server can resolve internal names, indicating that the local BIND service is functioning correctly for authoritative zones. However, external resolution fails, which typically means the server cannot reach upstream DNS servers. Outgoing UDP port 53 is required for DNS queries to external resolvers; if the firewall blocks this traffic, the server cannot forward queries to the internet, while internal queries (often served from local zones) remain unaffected.
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 server's /etc/resolv.conf points to itself.
Why it's wrong here
That is typical and not a problem as long as BIND listens on localhost.
✗
The forwarders directive is missing from named.conf.
Why it's wrong here
Without forwarders, BIND can still resolve using root hints, though slowly; it would not completely fail.
✓
The firewall is blocking UDP port 53 outgoing from the server.
Why this is correct
If outgoing DNS queries are blocked, external resolution fails, but internal zones can still be answered from local authoritative data.
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 named daemon is not running.
Why it's wrong here
If named were not running, internal resolution would also fail.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume missing forwarders (Option B) is the cause, but BIND can resolve externally via root hints without forwarders, so the real issue is a firewall blocking outbound UDP 53, which selectively breaks external resolution while internal resolution remains intact.
Detailed technical explanation
How to think about this question
DNS queries use UDP port 53 by default (TCP only for responses larger than 512 bytes or zone transfers). When a BIND resolver receives a query for an external name, it must contact root servers or forwarders over the network; a firewall blocking outbound UDP 53 prevents these packets from leaving the server, causing timeouts or SERVFAIL. In contrast, internal zones are served locally from the named daemon and do not require outbound traffic. Real-world scenarios often involve iptables rules that allow inbound DNS but forget to permit outbound queries.
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 practitioner preparing for the LPIC-2 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.
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.
Advanced Networking Configuration — This question tests Advanced Networking Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The firewall is blocking UDP port 53 outgoing from the server. — The server can resolve internal names, indicating that the local BIND service is functioning correctly for authoritative zones. However, external resolution fails, which typically means the server cannot reach upstream DNS servers. Outgoing UDP port 53 is required for DNS queries to external resolvers; if the firewall blocks this traffic, the server cannot forward queries to the internet, while internal queries (often served from local zones) remain unaffected.
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.
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Question Discussion
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