The function of DNS (Domain Name System) is primarily associated with which OSI layer?

• A. Layer 1
• B. Layer 3
• C. Layer 4
• D. Layer 7

Answer: (D)

The Domain Name System (DNS) primarily operates at Layer 7 of the OSI model, which is the Application Layer. This layer is responsible for facilitating communication between applications in a network. DNS serves as a critical service that translates human-readable domain names, like www.example.com, into IP addresses, which are necessary for network devices to locate each other and communicate effectively.

By functioning at the Application Layer, DNS interacts directly with end-user applications and services, enabling these programs to access network resources using easy-to-remember names instead of numerical IP addresses. This enhances user experience and simplifies web navigation, as users do not need to remember complex sequences of numbers.

Understanding DNS at this layer also helps to highlight its dependence on the transport protocols from the lower layers of the OSI model, including those involved in transmitting requests and responses over the network.