Understanding DNS Protocols and Network Naming

DNS Protocols and Services

In data networks, devices are labeled with a numeric IP address so they can participate in sending and receiving network messages. However, most people spend much time trying to remember these numerical addresses. Therefore, domain names were created to convert the numeric addresses into a simple and recognizable name.

The DNS protocol defines an automated service that matches resource names with the numeric network address requested.

Top Level Domains (TLDs)

The different top-level domains represent the kind of organization or the country of origin. Examples of top-level domains are:

• .au: Australia
• .co: Colombia
• .com: A firm or industry
• .jp: Japan
• .org: A nonprofit organization

The Application Layer

The application layer is responsible for direct access to the underlying processes that manage and deliver communication to the human network. This layer serves as the origin and destination of communications over data networks.

Applications, protocols, and services of the application layer allow users to interact with the data network significantly and effectively.

Key Components

• Applications: Computer programs with which the user interacts and initiates the transfer of data upon user request.
• Services: Background programs that provide a connection between the application layer and lower layer networking models.
• Protocols: Provide a framework of agreed rules and processes that ensure services running on a particular device can send and receive data from a variety of different network devices.

The delivery of network data can be requested from a server by a client, or between devices operating point-to-point, where the client-server relationship is established according to the source and destination device at the time. Messages are exchanged between the service application layer on each endpoint in accordance with the specifications of the protocol for establishing and using these relationships.

Protocol Examples

For example:

• Protocols like HTTP support sending Web pages to end devices.
• SMTP/POP support sending and receiving emails.
• SMB allows users to share files.
• DNS resolves the names used to refer to network resources into numerical addresses used by the network.