A SysOps administrator needs to configure a custom domain name (example.com) for a static website hosted on Amazon S3 and delivered via Amazon CloudFront. The domain name is managed by Amazon Route 53. Which type of Route 53 record should be created to point the custom domain name to the CloudFront distribution?
- AA CNAME record pointing to the S3 bucket URL.
- BAn ALIAS record pointing to the CloudFront distribution's domain name.
- CAn A record pointing to the CloudFront distribution's domain name.
- DA PTR record pointing to the CloudFront distribution's domain name.
Show answer & explanationAnswer & explanation
Correct answer: B. An ALIAS record pointing to the CloudFront distribution's domain name.
To map a root domain (like example.com) or a subdomain to a CloudFront distribution, an ALIAS record in Route 53 is the recommended and most efficient method. ALIAS records are a Route 53-specific extension to DNS that allow you to map your apex domain (e.g., example.com) directly to AWS resources like CloudFront distributions, without incurring DNS query charges and providing faster resolution than CNAMEs for apex domains.
Why the other options are wrong
- A. CNAME records cannot be used for apex domains (e.g., example.com) because they would conflict with other required records. It should also point to CloudFront, not S3 directly.
- C. An A record maps a domain name to an IP address. CloudFront distributions have dynamic IP addresses, making a static A record unsuitable. An ALIAS record functions like an A record but resolves to an AWS resource.
- D. PTR records are used for reverse DNS lookups, mapping an IP address to a domain name, which is not applicable here.
Route 53 ALIAS Record
A Route 53-specific record type that provides a CNAME-like functionality for apex domains (root domains) to AWS resources, such as CloudFront distributions, without the limitations of CNAMEs.
- Can be used for apex domains (e.g., example.com).
- Points to specific AWS resources (CloudFront, ELB, S3 bucket).
- No extra DNS query charges for ALIAS queries.
Memory trick: ALIAS is the special Route 53 record for your root domain's AWS shortcut.