How do DNS servers usually locate an IP address for a domain you asked about?

• A. By querying higher-level servers in the DNS hierarchy until the address is found.
• B. By guessing the IP address from the domain name.
• C. By consulting the user's web browser history.
• D. By requesting the IP from the operating system's ARP cache.

Answer: (A)

DNS resolves a domain by walking a hierarchy of name servers. When you ask for a domain, your device or its configured DNS resolver first checks its cache. If needed, the resolver starts at the root servers, which direct it to the appropriate top-level-domain servers (like the .com or .org servers). Those tell the resolver which authoritative server holds the domain’s records, and the resolver then queries that authoritative server to obtain the exact IP address. The result is returned to you (and cached for future requests) so subsequent lookups are faster. This process is how the system reliably translates a domain name into an IP.

Rough ideas like guessing the IP from the domain name aren’t reliable, browser history doesn’t help for new lookups, and ARP cache is used for local link-layer address resolution, not for locating IPs across the Internet.