220-1101 Question 110
Single answerAAAAA technician is configuring IPv6 connectivity for a small office workstation that can already reach local IPv4 resources but cannot access an internal application hosted only on IPv6. The application server has the IPv6 address 2001:db8:1:20::50. The technician confirms the workstation can successfully ping the server by IPv6 address, but users report they cannot reach the application when they enter its hostname. Which action should the technician take next to most likely resolve the issue?
- A
Create or correct the AAAA DNS record for the application host
- B
Add an A record that points the hostname to 127.0.0.1
- C
Disable IPv6 on the workstation so DNS uses IPv4 only
- D
Configure APIPA on the workstation to improve name resolution
Show answer and explanation
Correct answer: A
Explanation
This question tests practical understanding of AAAA records in DNS. In real-world troubleshooting, if a client can reach an IPv6-only server by address but not by hostname, the next step is to verify that DNS contains a valid AAAA record for that host. In DNS, an A record maps names to IPv4 addresses, while an AAAA record maps names to IPv6 addresses. This aligns with standard DNS behavior described in common networking documentation and is consistent with CompTIA A+ Core 1 expectations around TCP/IP, DNS, and IPv6 troubleshooting.
- A. Correct.
Correct. An AAAA record maps a hostname to an IPv6 address. If the workstation can reach the server directly by its IPv6 address but fails when using the hostname, the most likely issue is missing or incorrect DNS resolution for IPv6. Creating or fixing the AAAA record allows clients to resolve the hostname to 2001:db8:1:20::50.
- B. Incorrect.
Incorrect. An A record maps a hostname to an IPv4 address, not an IPv6 address. Pointing the name to 127.0.0.1 would direct traffic back to the client itself, not to the application server. This is a plausible distractor because candidates may confuse A and AAAA records.
- C. Incorrect.
Incorrect. Disabling IPv6 would not help users reach a service that is hosted only on IPv6. In fact, it would remove the working network path already verified by the successful IPv6 ping. This reflects the misconception that name resolution problems are fixed by forcing IPv4.
- D. Incorrect.
Incorrect. APIPA is an IPv4 self-assigned address range used when DHCP fails, typically 169.254.0.0/16. It does not improve DNS hostname resolution and is unrelated to creating IPv6 hostname mappings. This distractor targets confusion between address assignment and DNS records.