- A
Hashing of DNS responses without keys
Why wrong: Hashing alone does not provide authentication; DNSSEC uses public-key signatures.
- B
Digital signatures of DNS records
DNSSEC adds RRSIG records that are digital signatures over DNS data.
- C
Transport Layer Security for DNS
Why wrong: TLS secures the channel (DNS over TLS), but DNSSEC is about data origin authentication.
- D
Symmetric encryption of DNS queries
Why wrong: DNSSEC does not encrypt queries; it signs data.
Question 920 of 1,000
CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network 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.
A company deploys DNSSEC to protect its DNS infrastructure. Which cryptographic operation does DNSSEC primarily use to ensure the authenticity and integrity of DNS data?
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
✓
Digital signatures of DNS records
DNSSEC primarily uses digital signatures to ensure the authenticity and integrity of DNS data. Each DNS zone is signed with a private key, and resolvers verify the signatures using the corresponding public key, which is published as a DNSKEY record. This process allows the resolver to cryptographically confirm that the data has not been modified in transit and originates from the authoritative source.
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.
- ✗
Hashing of DNS responses without keys
Why it's wrong here
Hashing alone does not provide authentication; DNSSEC uses public-key signatures.
- ✓
Digital signatures of DNS records
Why this is correct
DNSSEC adds RRSIG records that are digital signatures over DNS data.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Transport Layer Security for DNS
- ✗
Symmetric encryption of DNS queries
Why it's wrong here
DNSSEC does not encrypt queries; it signs data.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing DNSSEC's use of digital signatures for data origin authentication with encryption or transport-layer security, leading candidates to incorrectly select TLS or symmetric encryption options.
Detailed technical explanation
How to think about this question
Under the hood, DNSSEC adds four new resource record types: RRSIG (contains the digital signature), DNSKEY (holds the public signing key), DS (delegation signer for chain of trust), and NSEC/NSEC3 (for authenticated denial of existence). The signing process uses algorithms like RSA/SHA-256 or ECDSA P-256 (RFC 8624), and validation involves walking the chain of trust from the root zone trust anchor (e.g., root KSK published by IANA) down to the queried record. A subtle behavior is that DNSSEC does not encrypt DNS data—it only signs it, so queries and responses remain in plaintext; confidentiality requires additional protocols like DNS over TLS (DoT) or DNS over HTTPS (DoH).
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Visual reference
Quick reference
Common DNS Record Types
| Record | Purpose | Example |
|---|---|---|
| A | IPv4 address mapping | example.com → 93.184.216.34 |
| AAAA | IPv6 address mapping | example.com → 2606:2800::1 |
| CNAME | Alias to another hostname | www → example.com |
| MX | Mail server for domain | example.com → mail.example.com (priority 10) |
| TXT | Text data (SPF, DKIM, verification) | v=spf1 include:_spf.example.com ~all |
| NS | Authoritative name servers | example.com NS ns1.example.com |
| PTR | Reverse DNS (IP → hostname) | 34.216.184.93.in-addr.arpa → example.com |
| SOA | Zone authority record | Primary NS, admin email, serial, TTL defaults |
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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FAQ
Questions learners often ask
What does this CISSP question test?
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Digital signatures of DNS records — DNSSEC primarily uses digital signatures to ensure the authenticity and integrity of DNS data. Each DNS zone is signed with a private key, and resolvers verify the signatures using the corresponding public key, which is published as a DNSKEY record. This process allows the resolver to cryptographically confirm that the data has not been modified in transit and originates from the authoritative source.
What should I do if I get this CISSP 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: Jul 4, 2026
This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
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