- A
PTR record
Why wrong: PTR record is used for reverse DNS lookup.
- B
AAAA record
AAAA record maps a hostname to an IPv6 address.
- C
A record
Why wrong: A record maps to an IPv4 address.
- D
CNAME record
Why wrong: CNAME is an alias to another canonical name.
Question 851 of 1,000
200-901 Network Fundamentals Practice Question
This 200-901 practice question tests your understanding of network fundamentals. 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 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?
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
✓
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.
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.
- ✗
PTR record
Why it's wrong here
PTR record is used for reverse DNS lookup.
- ✓
AAAA record
Why this is correct
AAAA record maps a hostname to an IPv6 address.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A record
Why it's wrong here
A record maps to an IPv4 address.
- ✗
CNAME record
Why it's wrong here
CNAME is an alias to another canonical name.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
In DNS, the AAAA record stores a 128-bit IPv6 address, while the A record stores a 32-bit IPv4 address. When a microservice performs a DNS query for 'payment-service.example.com' with a request for AAAA records, the DNS resolver returns the IPv6 address, enabling direct communication over IPv6. This is critical in modern networks where IPv6-only or dual-stack environments are common, and service discovery relies on DNS-based resolution.
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 junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
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
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FAQ
Questions learners often ask
What does this 200-901 question test?
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 200-901 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.
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Last reviewed: Jul 4, 2026
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.
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