200-901 Network Fundamentals Practice Question
A developer is designing a microservices architecture where services need to discover each other using DNS. The team wants to map a service name 'payment-service.example.com' to its IPv6 address. Which DNS record type should be used?
⚠ Common exam trap
Cisco often tests the distinction between A and AAAA records, and the trap here is that candidates may confuse the AAAA record with the A record or incorrectly think a CNAME can resolve to an IP address directly.
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
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AAAA record
The AAAA record (Quad-A) is the correct DNS record type for mapping a hostname to an IPv6 address, as defined in RFC 3596. Since the requirement is specifically to resolve 'payment-service.example.com' to an IPv6 address, the AAAA record is the appropriate choice.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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PTR record
Why it's wrong here
A PTR record performs reverse DNS, mapping an IP address back to a hostname in ip6.arpa; it cannot resolve a forward name to an IPv6 address. An AAAA record provides that forward mapping. PTR suits reverse lookups for logging or mail verification.
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AAAA record
Why this is correct
AAAA records map a hostname to an IPv6 address, exactly matching the requirement to resolve 'payment-service.example.com' to its IPv6 address. The A record serves the same purpose for IPv4 only, so it cannot satisfy the IPv6 constraint.
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A record
Why it's wrong here
An A record maps a hostname to a 32-bit IPv4 address only; it cannot hold an IPv6 address. An AAAA record maps the service name to its 128-bit IPv6 address. A records remain correct for IPv4-only service discovery.
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CNAME record
Why it's wrong here
A CNAME aliases one hostname to another canonical name; it cannot point directly at an IPv6 address, and the target must itself resolve. An AAAA record maps the service name straight to the IPv6 address. CNAME suits aliasing, for example www to a hostname.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco 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 200-901 exam.