Computer Networking glossary

This computer-networking glossary defines, in one sentence, the key terms from our courses: TCP/IP, VLAN, routing, firewall, Wi-Fi… Each definition stands on its own and, where relevant, points to the related course.

Network (LAN / WAN)

A network links devices to exchange data: a LAN is local (an office), a WAN spans long distances (sites, the internet).

OSI model

The OSI model describes network communication in 7 layers (physical to application); it is a reference framework for understanding and troubleshooting. See network theory.

TCP/IP

TCP/IP is the internet protocol suite: IP routes packets, TCP ensures their reliable delivery.

IP address

An IP address identifies a device on a network (IPv4 such as 192.168.1.10, or IPv6).

Subnet & mask

The subnet mask splits a network into smaller segments to organise addressing and limit broadcast traffic.

Switch

A switch connects devices on a local network and forwards frames to the right port (layer 2). See switching.

VLAN

A VLAN logically segments one physical network into several isolated networks, for security and organisation.

Router & routing

A router connects different networks and chooses the path packets take between them. See routing & firewalling.

Gateway

The gateway is the device through which a machine leaves its local network towards other networks.

DNS

DNS translates domain names (example.com) into IP addresses.

DHCP

DHCP automatically assigns IP addresses and network settings to devices.

NAT

NAT translates private IP addresses into a public one to reach the internet.

Firewall

A firewall filters traffic according to security rules. See the Fortinet NSE4 course.

VPN

A VPN creates an encrypted tunnel over the internet to securely connect remote sites or users.

Wi-Fi

Wi-Fi is wireless local networking; its design and security are a topic in their own right. See Wi-Fi & mobility.

QoS

QoS (Quality of Service) prioritises certain flows (voice, video) to guarantee their performance on the network.

Cloud networking

Cloud networking (VPCs, subnets, gateways) organises connectivity in Azure, AWS or GCP. See cloud networking.

CCNA

CCNA is Cisco’s flagship networking certification (routing, switching, security). See the CCNA track.