What is the purpose of DNS A, AAAA, MX, and CNAME records?

• A. A records map hostnames to IPv4 addresses; AAAA records map hostnames to IPv6 addresses; MX records identify mail exchangers; CNAME records provide an alias for another domain.
• B. A records map hostnames to IPv6 addresses; AAAA records map hostnames to IPv4 addresses; MX records identify mail exchangers; CNAME records provide a path to DNSSEC.
• C. MX records map hostnames to IP addresses; A records map hostnames to IPv4 addresses; CNAME records identify alias; AAAA records map to IPv6 addresses.
• D. CNAME records map hostnames to IP addresses; A records identify mail exchangers; AAAA records alias a domain to another domain; MX records map hostnames to IPv4 addresses.

Answer: (A)

In DNS, each record type serves a specific role in translating names to the resources you need. An A record maps a hostname to an IPv4 address, allowing a client to reach a host using IPv4. An AAAA record does the same for IPv6 addresses. An MX record identifies the mail exchanger for a domain, telling mail systems which server should handle email for that domain (often with a priority value). A CNAME record creates an alias from one domain name to another canonical domain name, so requests for the alias are treated as requests for the target name.

This combination—A for IPv4, AAAA for IPv6, MX for mail servers, and CNAME for aliasing to another domain—is the standard way DNS handles these different needs.