- A
The company's mail server is not authorized to relay mail for the internal clients, causing a deferral.
Why wrong: Relay authorization failures produce 'Relay access denied' errors, not connection timeouts.
- B
The DNS MX record for example.org is misconfigured, pointing to a non-existent host.
Why wrong: If MX record pointed to non-existent host, Postfix would get a DNS resolution failure, not a connection timeout.
- C
The remote mail server mx.example.org is blocking connections from the company's mail server IP.
Connection timed out suggests the remote server is not responding, often due to firewall or server issues.
- D
The remote server is rate limiting connections from the company's mail server.
Why wrong: Rate limiting typically produces a temporary failure after connection is established, not a timeout.
Quick Answer
The answer is that the remote mail server mx.example.org is blocking connections from the company’s IP, as the “Connection timed out” log entry shows Postfix resolved the MX record correctly but failed to complete the TCP handshake on port 25, which points to a firewall or ACL drop rather than a DNS or routing issue. On the LPIC-2 exam, this scenario tests your ability to distinguish between a timeout caused by remote blocking versus a local misconfiguration or rate-limiting, which would produce different log messages like “too many connections” or “name service error.” A common trap is confusing a timeout with a transient network failure, but remember that a persistent timeout on a specific domain strongly suggests the remote server is actively refusing your IP. Memory tip: “Timeout on port 25 means the firewall is alive, but not for you.”
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 runs a Postfix mail server that relays mail for internal clients. Users report that emails to a specific external domain 'example.org' are delayed by several hours. The administrator checks the mail logs and sees entries like: 'status=deferred (connect to mx.example.org[203.0.113.10]:25: Connection timed out)'. 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 choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The remote mail server mx.example.org is blocking connections from the company's mail server IP.
The log entry 'Connection timed out' indicates that the company's Postfix server successfully resolved the MX record for example.org to the IP 203.0.113.10 but could not establish a TCP connection to port 25 on that host. This is consistent with the remote server explicitly blocking inbound connections from the company's IP, often via a firewall rule or access control list, rather than a DNS or rate-limiting issue.
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 company's mail server is not authorized to relay mail for the internal clients, causing a deferral.
Why it's wrong here
Relay authorization failures produce 'Relay access denied' errors, not connection timeouts.
- ✗
The DNS MX record for example.org is misconfigured, pointing to a non-existent host.
Why it's wrong here
If MX record pointed to non-existent host, Postfix would get a DNS resolution failure, not a connection timeout.
- ✓
The remote mail server mx.example.org is blocking connections from the company's mail server IP.
Why this is correct
Connection timed out suggests the remote server is not responding, often due to firewall or server issues.
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 remote server is rate limiting connections from the company's mail server.
Why it's wrong here
Rate limiting typically produces a temporary failure after connection is established, not a timeout.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 'deferred' with a relay authorization issue or a DNS problem, but the specific 'Connection timed out' error points to a network-layer block rather than an SMTP-level rejection or misconfiguration.
Detailed technical explanation
How to think about this question
When Postfix encounters a 'Connection timed out' on port 25, it means the TCP SYN packet sent to the remote server received no SYN-ACK response within the kernel's default timeout (often 30–120 seconds). This is distinct from a connection refused (RST) or a banner timeout. In real-world scenarios, remote mail servers often implement greylisting or IP-based blacklisting, but those generate SMTP-level responses; a silent drop of the SYN packet is typical of a firewall rule that denies the source IP without sending a reject message, forcing Postfix to retry with increasing intervals (e.g., after 1, 5, 15 minutes) until the queue expires.
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.
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DNS, Web and Mail Services — study guide chapter
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FAQ
Questions learners often ask
What does this LPIC-2 question test?
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 remote mail server mx.example.org is blocking connections from the company's mail server IP. — The log entry 'Connection timed out' indicates that the company's Postfix server successfully resolved the MX record for example.org to the IP 203.0.113.10 but could not establish a TCP connection to port 25 on that host. This is consistent with the remote server explicitly blocking inbound connections from the company's IP, often via a firewall rule or access control list, rather than a DNS or rate-limiting issue.
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
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Last reviewed: Jun 11, 2026
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.
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