Which is used to resolve a fully-qualified domain name (FQDN) to an IP address?

To resolve a fully-qualified domain name (FQDN) to an IP address, a DNS query is used. The Domain Name System (DNS) is a hierarchical naming system that translates human-readable domain names, like www.example.com, into machine-readable IP addresses, such as 192.0.2.1. This is essential for computers and networking devices to locate resources on the internet, as they communicate using numeric IP addresses rather than domain names.

When a user enters a domain name in their browser, the operating system checks the local DNS cache. If the IP address is not in the cache, the operating system sends a DNS query to a DNS server, which then performs the necessary lookups to resolve the domain name into the corresponding IP address. The resolved IP address is then returned to the requesting device, allowing it to establish a connection to the correct server.

In contrast, other options relate to different aspects of networking and communication. HTTP requests pertain to web page requests, FTP commands are used for file transfers, and ARP requests are involved in mapping IP addresses to MAC addresses on a local network, but none are used for resolving FQDNs to IP addresses.