Which Application Layer protocol is used to resolve domain names to IP addresses?

Which Application Layer protocol is used to resolve domain names to IP addresses?

• A. Dynamic Host Configuration Protocol
• B. Simple Mail Transfer Protocol
• C. Hypertext Transfer Protocol
• D. Domain Name System

Answer: (D)

DNS resolves human-readable domain names to IP addresses, so applications can connect to the correct servers without users needing to remember numeric addresses. When a client needs a resource, it asks a DNS resolver, which queries a hierarchy of DNS servers (root, top-level domain, and authoritative servers) and returns the corresponding IP address. The client then uses that IP to establish the connection. DNS is typically carried over UDP on port 53, with TCP used for larger responses or zone transfers. This lookup capability is essential for accessing websites and healthcare information systems smoothly, since it translates names like example.com into the actual address computers use to route traffic. The other options serve different functions: one protocol assigns IP addresses automatically on a local network, another transfers email, and another retrieves web content—none perform domain name resolution.

DNS resolves human-readable domain names to IP addresses, so applications can connect to the correct servers without users needing to remember numeric addresses. When a client needs a resource, it asks a DNS resolver, which queries a hierarchy of DNS servers (root, top-level domain, and authoritative servers) and returns the corresponding IP address. The client then uses that IP to establish the connection. DNS is typically carried over UDP on port 53, with TCP used for larger responses or zone transfers. This lookup capability is essential for accessing websites and healthcare information systems smoothly, since it translates names like example.com into the actual address computers use to route traffic.

The other options serve different functions: one protocol assigns IP addresses automatically on a local network, another transfers email, and another retrieves web content—none perform domain name resolution.