The DNS record that allows you to alias both services to the same record (IP address).

The DNS record that allows you to alias both services to the same record (IP address).

• A. A
• B. MX
• C. PTR
• D. CNAME

Answer: (D)

This question hinges on how DNS can make multiple names share the same IP by aliasing. A CNAME record creates an alias from one domain name to another domain name. You can point several service names to a single canonical name, and that canonical name has an A (or AAAA) record with the actual IP address. When a resolver looks up any of the alias names, it follows the CNAME to the canonical name and then retrieves the IP from its A/AAAA record. So, both services end up resolving to the same IP address through that single canonical name. By contrast, an A record directly maps a name to an IP, MX specifies mail servers, and PTR is for reverse DNS mappings, none of which provide the aliasing behavior described.

This question hinges on how DNS can make multiple names share the same IP by aliasing. A CNAME record creates an alias from one domain name to another domain name. You can point several service names to a single canonical name, and that canonical name has an A (or AAAA) record with the actual IP address. When a resolver looks up any of the alias names, it follows the CNAME to the canonical name and then retrieves the IP from its A/AAAA record. So, both services end up resolving to the same IP address through that single canonical name. By contrast, an A record directly maps a name to an IP, MX specifies mail servers, and PTR is for reverse DNS mappings, none of which provide the aliasing behavior described.