Network

The Application Layer’s Role The Application Layer (Layer 7) is the layer the user interacts with. Its job is to provide specific services and translate user input into the structures required by the Transport Layer (Part 66). Protocol 1: DNS (Domain Name Service) Users prefer typing names (google.com) rather than IP addresses. DNS is the protocol that translates these human-readable names into the 4-byte IP addresses required by the Network Layer. ...

The OSI Model and the Transport Layer The Transport Layer (Layer 4) is the crucial link between the application and the network. Its job is to ensure that data is delivered reliably (TCP) or quickly (UDP) between specific applications (identified by port numbers). Protocol 1: Connectionless (UDP Concepts) A connectionless protocol is fast but unreliable. Data is sent as individual datagrams without confirmation of receipt. This is ideal for time-sensitive data like video frames or game state updates. ...

The OSI Model and the Network Layer The Network Layer (Layer 3 of the OSI model) is responsible for logical addressing (e.g., IP addresses) and routing data packets between different networks. This is where your simple 4-byte addresses come into play. Goal: To wrap the Link Layer frame (Part 64) with a header that includes a Source Address and a Destination Address. Defining the Packet Structure Our simple network packet (often called a datagram) needs to sit inside the Link Layer frame and contain the necessary addressing information. ...

The OSI Model and the Link Layer Networking is organized into layers. The Link Layer (Layer 2 of the OSI model) is the lowest level of communication, responsible for sending and receiving frames (raw data packets) between two connected devices (e.g., two computers on a local network). Goal: To wrap user data with a small header and footer so the receiver knows where the packet begins, where it ends, and whether it’s valid. ...