ANS-C01 Question 256
Select 2An e-commerce application hosted on AWS is experiencing intermittent connectivity issues. The application uses a custom domain (e.g., www.example.com) that is configured in Amazon Route 53 with an A record pointing to an Application Load Balancer (ALB). During troubleshooting, you find that some users are unable to resolve the domain to an IP address. Which of the following steps would most likely resolve the issue?
- A
Verify that the TTL (Time to Live) value for the DNS record in Route 53 is appropriately set for dynamic IP resolution.
- B
Ensure the ALB's DNS name is correctly mapped to the A record in Route 53.
- C
Check whether the Route 53 hosted zone is configured as a private hosted zone and if it has the correct VPC associations.
- D
Inspect the health checks configured in Route 53 and ensure they are passing for the target ALB.
- E
Verify that the name servers listed in the domain registrar are the same as those provided by the Route 53 hosted zone.
Show answer and explanation
Correct answers: B, E
Explanation
For a domain to resolve correctly to an IP address, the DNS configuration must be accurate. Ensuring the ALB's DNS name is correctly mapped to the A record in Route 53 ensures the domain resolves to the correct endpoint. Additionally, the name servers at the domain registrar must point to the Route 53 hosted zone's name servers, as this ensures DNS queries are directed to the correct AWS-hosted configuration.
- A. Incorrect.
While TTL can affect how quickly DNS changes propagate, it is not directly related to resolving the domain to an IP address in this scenario.
- B. Correct.
If the ALB's DNS name is not correctly mapped to the A record in Route 53, users will not be able to resolve the domain to an IP address.
- C. Incorrect.
A private hosted zone would only impact the resolution if the domain is intended to be private, which is not the case here since the domain is public-facing.
- D. Incorrect.
Route 53 health checks are used for routing traffic to healthy endpoints, but they do not directly impact DNS resolution for the domain.
- E. Correct.
If the name servers at the domain registrar do not match the Route 53 hosted zone's name servers, DNS queries will fail to resolve the domain.