- A
The 'allow-transfer' ACL is used to restrict which clients can perform recursive queries.
Why wrong: allow-transfer restricts zone transfers, not recursion.
- B
The 'allow-recursion' ACL can be used to restrict which clients can use the server's recursive lookup feature.
allow-recursion limits recursive queries to specific clients.
- C
The 'blackhole' ACL can be used to prevent cache poisoning attacks.
Why wrong: blackhole discards queries from certain sources, but does not prevent cache poisoning; DNSSEC does.
- D
The 'forwarders' option can be used to disable recursion entirely.
Why wrong: forwarders only redirect queries; recursion can be disabled with 'recursion no'.
- E
The 'allow-query' ACL can be used to restrict which clients can send DNS queries to the server.
allow-query limits the IP addresses that can query the server.
Quick Answer
The correct answer is that the 'allow-query' ACL restricts which clients can send DNS queries to the server, while the 'allow-recursion' ACL controls which clients are permitted to use the server's recursive query feature. This distinction is critical because restricting recursion to trusted clients prevents the server from being exploited in DNS amplification attacks and reduces the risk of cache poisoning, as unauthorized clients cannot force the server to resolve external domains on their behalf. On the LPIC-2 exam, this topic tests your understanding of BIND security ACLs within the DNS configuration domain, often appearing in scenario-based questions where you must choose the correct directive to mitigate specific threats like open resolver abuse. A common trap is confusing 'allow-query' (which controls all queries, including authoritative) with 'allow-recursion' (which only controls recursive lookups); remember that blocking recursion alone does not stop direct zone transfers or queries to authoritative data. Memory tip: "Query for anyone, Recursion for friends only."
LPIC-2 DNS, Web and Mail Services Practice Question
This LPIC-2 practice question tests your understanding of dns, web and mail services. 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 statements are true regarding BIND DNS server security? (Choose two.)
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 'allow-recursion' ACL can be used to restrict which clients can use the server's recursive lookup feature.
Option B is correct because the 'allow-recursion' ACL in BIND explicitly controls which clients are permitted to use the server's recursive query feature. By restricting recursion to trusted clients, the server avoids being used in amplification attacks and reduces exposure to cache poisoning. This ACL is defined in the options block or per-zone and can reference address match lists or named ACLs.
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 'allow-transfer' ACL is used to restrict which clients can perform recursive queries.
Why it's wrong here
allow-transfer restricts zone transfers, not recursion.
- ✓
The 'allow-recursion' ACL can be used to restrict which clients can use the server's recursive lookup feature.
Why this is correct
allow-recursion limits recursive queries to specific clients.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The 'blackhole' ACL can be used to prevent cache poisoning attacks.
Why it's wrong here
blackhole discards queries from certain sources, but does not prevent cache poisoning; DNSSEC does.
- ✗
The 'forwarders' option can be used to disable recursion entirely.
Why it's wrong here
forwarders only redirect queries; recursion can be disabled with 'recursion no'.
- ✓
The 'allow-query' ACL can be used to restrict which clients can send DNS queries to the server.
Why this is correct
allow-query limits the IP addresses that can query the server.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing the purpose of 'allow-transfer' (zone transfer restriction) with recursion control, and assuming 'forwarders' disables recursion when it actually just redirects queries to another resolver.
Detailed technical explanation
How to think about this question
In BIND, ACLs like 'allow-recursion' and 'allow-query' are evaluated at different stages of query processing: 'allow-query' controls initial query acceptance, while 'allow-recursion' gates the recursive resolution path. A common real-world scenario is configuring a split DNS where internal clients get recursion for private zones, while external clients are limited to authoritative responses only. The 'blackhole' ACL simply drops packets from listed sources, but cache poisoning exploits vulnerabilities in the resolution process itself, not source IP filtering.
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.
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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 'allow-recursion' ACL can be used to restrict which clients can use the server's recursive lookup feature. — Option B is correct because the 'allow-recursion' ACL in BIND explicitly controls which clients are permitted to use the server's recursive query feature. By restricting recursion to trusted clients, the server avoids being used in amplification attacks and reduces exposure to cache poisoning. This ACL is defined in the options block or per-zone and can reference address match lists or named ACLs.
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.
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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