What is a DNS A record and what does it map?

What is a DNS A record and what does it map?

• A. An IPv4 address to a domain name.
• B. A domain name to an IPv4 address.
• C. A domain name to a port number.
• D. A domain name to an IPv6 address.

Answer: (B)

A DNS A record is a mapping from a domain name to an IPv4 address. When a client looks up a domain, the DNS server responds with the IPv4 address so the client can reach the server over the regular Internet protocol. This is how your browser learns where to send requests for a site using IPv4 addresses. It doesn’t map a domain name to a port number—ports are part of the transport layer, not DNS. It also isn’t used to map to an IPv6 address; that would require an AAAA record. And reverse mappings from an IP back to a domain use PTR records, not A records.

A DNS A record is a mapping from a domain name to an IPv4 address. When a client looks up a domain, the DNS server responds with the IPv4 address so the client can reach the server over the regular Internet protocol. This is how your browser learns where to send requests for a site using IPv4 addresses.

It doesn’t map a domain name to a port number—ports are part of the transport layer, not DNS. It also isn’t used to map to an IPv6 address; that would require an AAAA record. And reverse mappings from an IP back to a domain use PTR records, not A records.