A computer network
is a digital telecommunications network that allows nodes to share resources.
Nodes:
- Router
- Switch
- Firewall
- Server
- Client
Client vs Server
- Client — a device that accesses a service made available by a server.
- Server — a device that provides functions or services for clients.
Switch
- Provides connectivity within the same LAN.
- Forwards traffic within the same LAN.
- Has many ports (usually 24+).
- Does not provide connectivity between LANs or over the internet.
Router
- Provides connectivity between LANs.
- Sends data over the internet.
- Has fewer network interfaces than switches.
Firewall
A firewall (or a next-generation firewall) monitors and controls network traffic based on configured rules. It can be placed inside (after the router) or outside the network (before the router).
There are two types of firewalls:
- Network hardware device that filters traffic between networks.
- Host-based firewall — a software application that filters traffic entering and exiting a host.
Examples of Devices
| Device Type | Examples |
|---|---|
| Switches | Cisco Catalyst Switch 9200, 3650 |
| Routers | ISR 1000, 900, 4000 |
| Firewalls | ASA5500-X, Firepower 2100 |
📌 These are personal study notes. Please read the full disclaimer for more information.
Category: CCNA