This LPIC-1 practice question tests your understanding of essential system services and networking. 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 mail server using Postfix is rejecting emails from a partner domain. The administrator checks the maillog and sees 'relay access denied'. Which Postfix configuration parameter is most likely misconfigured?
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.
mydestination
Why wrong: mydestination specifies domains for which this server accepts mail.
inet_interfaces
Why wrong: inet_interfaces defines network interfaces to listen on.
relayhost
Why wrong: relayhost is for forwarding all outgoing mail.
mynetworks
mynetworks specifies IP ranges allowed to relay.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
mynetworks
Option A is correct: `mynetworks` defines which clients can relay through the server. Option B (mydestination) defines local domains. Option C (relayhost) is for outbound relay. Option D (inet_interfaces) controls which interfaces to listen on.
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.
mydestination
Why it's wrong here
mydestination specifies domains for which this server accepts mail.
inet_interfaces
Why it's wrong here
inet_interfaces defines network interfaces to listen on.
relayhost
Why it's wrong here
relayhost is for forwarding all outgoing mail.
mynetworks
Why this is correct
mynetworks specifies IP ranges allowed to relay.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
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 LPIC-1 NAT questions on configuration and troubleshooting.
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FAQ
Essential System Services and Networking — This question tests Essential System Services and Networking — Static NAT maps one inside address to one outside address..
The correct answer is: mynetworks — Option A is correct: `mynetworks` defines which clients can relay through the server. Option B (mydestination) defines local domains. Option C (relayhost) is for outbound relay. Option D (inet_interfaces) controls which interfaces to listen on.
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 LPIC-1 NAT questions on configuration and troubleshooting.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 24, 2026
This LPIC-1 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-1 exam.
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