This LPIC-2 practice question tests your understanding of system security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO commands can be used to list currently loaded iptables rules in the filter table? (Choose two.)
iptables -L -t nat
Why wrong: Lists rules in nat table, not filter.
iptables -nL
Lists rules numerically (default filter table).
iptables -L -t filter
Lists rules in filter table.
iptables -Z
Why wrong: Zeroes counters, not list.
iptables -F
Why wrong: Flushes rules, not list.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
iptables -nL
Options A and C are correct. 'iptables -L -t filter' lists rules in filter table; 'iptables -nL' lists rules numerically without DNS resolution. Option B is wrong because 'iptables -S' prints rule specifications, not a list? Actually 'iptables -S' prints rules in iptables-save format, which is a list. So B is also a way to list rules. Wait, -S is also valid. The question says 'list currently loaded iptables rules', and -S does list them. So we have three correct? Let's check: A: iptables -L -t filter (filter is default), C: iptables -nL (numeric list), B: iptables -S (list rules in command form). The question asks for TWO. Which two are most commonly used? The exam might consider -L and -nL as similar, but -L with -t filter is explicit. However, -S is also valid. To avoid ambiguity, I'll make D and E clearly wrong. Let's change options: A: iptables -L -t filter, B: iptables -L -t nat, C: iptables -nL, D: iptables -F, E: iptables -Z. So correct: A and C. B lists nat table, not filter. D flushes, E zeroes counters. So that works.
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.
iptables -L -t nat
Why it's wrong here
Lists rules in nat table, not filter.
iptables -nL
Why this is correct
Lists rules numerically (default filter table).
Related concept
Static NAT maps one inside address to one outside address.
iptables -L -t filter
Why this is correct
Lists rules in filter table.
Related concept
Static NAT maps one inside address to one outside address.
iptables -Z
Why it's wrong here
Zeroes counters, not list.
iptables -F
Why it's wrong here
Flushes rules, not list.
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-2 NAT questions on configuration and troubleshooting.
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FAQ
System Security — This question tests System Security — Static NAT maps one inside address to one outside address..
The correct answer is: iptables -nL — Options A and C are correct. 'iptables -L -t filter' lists rules in filter table; 'iptables -nL' lists rules numerically without DNS resolution. Option B is wrong because 'iptables -S' prints rule specifications, not a list? Actually 'iptables -S' prints rules in iptables-save format, which is a list. So B is also a way to list rules. Wait, -S is also valid. The question says 'list currently loaded iptables rules', and -S does list them. So we have three correct? Let's check: A: iptables -L -t filter (filter is default), C: iptables -nL (numeric list), B: iptables -S (list rules in command form). The question asks for TWO. Which two are most commonly used? The exam might consider -L and -nL as similar, but -L with -t filter is explicit. However, -S is also valid. To avoid ambiguity, I'll make D and E clearly wrong. Let's change options: A: iptables -L -t filter, B: iptables -L -t nat, C: iptables -nL, D: iptables -F, E: iptables -Z. So correct: A and C. B lists nat table, not filter. D flushes, E zeroes counters. So that works.
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-2 NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 24, 2026
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