Chapter 1.1: Understanding Computer Networks

1. Computer Network

A computer network consists of interconnected computers that share resources. Each computer, referred to as a node, can connect through wired or wireless methods. Examples include:

• Local Area Network (LAN): Connects computers within a small area.
• Wide Area Network (WAN): Connects computers over extensive geographical distances, such as the Internet.

2. Client

A client is a computer node that requests resources within a network. For instance, your computer acts as a client when using a browser to access your Medium profile.

3. Server

Conversely, a server is a computer node that hosts and supplies resources to other nodes. For example, the server containing your Medium profile data sends it back to your browser upon request.

4. Open Systems Interconnection (OSI) Model

The OSI model is a framework that divides communication between computer nodes into seven abstraction layers:

• Layer 1: Physical Layer
• Layer 2: Data Link Layer
• Layer 3: Network Layer
• Layer 4: Transport Layer
• Layer 5: Session Layer
• Layer 6: Presentation Layer
• Layer 7: Application Layer

5. TCP/IP Model

This model condenses the OSI framework into four layers, reflecting current Internet implementations:

• Layer 1: Network Access Layer
• Layer 2: Internet Layer
• Layer 3: Transport Layer
• Layer 4: Application Layer

6. Network Protocol

Protocols are a set of guidelines that dictate how data is exchanged between computer nodes in a network.

7. Internet Protocol

This set of rules operates in the Internet layer of TCP/IP, overseeing the transmission of data packets from the source to the destination based on IP addresses. There are two versions: IPv4 and IPv6.

8. Transmission Control Protocol (TCP)

TCP is a rule set in the Transport layer that ensures reliable data transmission between nodes. It establishes a connection before any data packets are sent.

9. 3-Way Handshake Process

This process outlines how a TCP connection is set up, akin to a phone call:

• SYN: The client initiates a connection with a SYN signal, similar to dialing a number.
• SYN + ACK: The server acknowledges the request with a SYN-ACK signal, akin to greeting the caller.
• ACK: The client completes the handshake by sending an ACK signal, confirming the connection.

10. User Datagram Protocol (UDP)

UDP, part of the Transport layer, allows data packets to be sent without requiring a fixed connection. This connectionless protocol supports rapid data transmission.

Thanks for reading! Stay tuned for the next part.