Exchanging Data: Networks

Data exchange or communication between two devices can happen via a network.
Networks are interconnected system of devices that allow the sharing of resources and information.
Networks can be classified as Local Area Networks (LAN), Metropolitan Area Networks (MAN), Wide Area Networks (WAN), or Personal Area Networks (PAN) depending on the geographical spread.
Key components of a network include: end devices (computers, servers, smartphones etc.), intermediary devices (routers, switches), network media (wires, cables, wireless signals) and network protocols.
Protocols are a set of rules that govern data communication - common examples include HTTP, HTTPS, FTP, SMTP, DNS.
Router is a hardware device that routes data from a local network to other network link while a switch connects devices on a network and uses packet switching to receive, process and forward data to the destination device.
Network topologies describe the physical or logical arrangement of the devices on the network; common types include star, mesh, bus, ring topologies.
IP addresses are used to identify devices on a network; two versions of IP addresses are currently in use - IPv4 and IPv6.
The Internet is a global WAN that connects devices across the world; it works on the TCP/IP model where TCP is responsible for the data delivery of a packet and IP is responsible for the logical addressing.
Security is a crucial aspect of networks to protect data and systems from threats and attacks; common security measures include firewalls, encryption, user authentication and regular updates.
Network performance can be influenced by many factors, including the transmission media type, the number of devices on the network, the capacity of the hardware and software, and the data traffic levels.
Virtual Private Networks (VPN) create a safe and encrypted connection over a less secure network, such as the internet.
Networks can be categorised into peer-to-peer (P2P) where all computers are equal and can access each other’s files or Client/server where one or more computers (servers) have central control over the network.
The OSI model describes the processes for transmission of data over a network, splitting these processes into seven layers: Physical, Data Link, Network, Transport, Session, Presentation, Application.