Networks and Their Types
Unit 1: Networking Foundations. Lesson 1 of 49 in NetPlus Academy.
A network is two or more devices that can exchange data. Everything on the exam builds on a few ways of describing networks: by how far they reach and by who is in charge.
Networks by reach
- LAN (local area network): one building or campus, high speed, owned by one organization.
- WLAN: a LAN delivered over Wi-Fi.
- WAN (wide area network): connects LANs across cities or countries, usually over links leased from a provider. The internet is the largest WAN.
- MAN: a metro-sized network, bigger than a LAN, smaller than a WAN.
- PAN: a personal-scale network such as Bluetooth between a phone and headphones.
- SAN: a storage area network that gives servers block-level access to disk arrays, separate from the user network.
Networks by control
- Client-server: dedicated servers hold resources and enforce access. Scales well and is what you will see in business.
- Peer-to-peer: every host shares and consumes directly. Cheap, but every device manages its own security, so it does not scale.
Networks and Their Types, explained slowly
Start with one idea
A network is nothing more than devices that can pass data to each other. Two laptops and a cable is a network. So is the internet. Every term in this lesson is just a way of describing one of two things: how far the network reaches, or who is in charge of it.
Reach: how far does it go?
Think of it as distances you would travel.
PAN LAN MAN WAN arm's one one between cities, reach building city countries, the world
- PAN: your phone talking to your earbuds over Bluetooth. Personal space.
- LAN: one office, one building, one campus. Fast, and you own all the equipment. A WLAN is the same thing delivered by Wi-Fi instead of cables.
- MAN: a city. Picture a hospital with three buildings across town joined by fiber the city runs under the streets. Too big to be one LAN, too small to be a WAN.
- WAN: offices in Denver and Atlanta joined by circuits you rent from a carrier. The internet is the biggest WAN there is.
- SAN: the odd one out. A storage area network is not about distance at all. It is a separate network that connects servers to big disk arrays. "Block-level" means the server sees the storage as if it were its own hard drive, not as a shared folder.
Control: who is in charge?
Picture a library. In a client-server network there is a librarian: a dedicated server that holds the files, the user accounts, and the printers. Want to change someone's password? One place. Want to back up everything? One place. That is why every business runs this way.
In a peer-to-peer network there is no librarian. Everyone lends books directly. Each PC shares its own folders and keeps its own list of who is allowed in. With five PCs that is fine. With fifty, every new employee needs an account on every machine, and nobody knows where the important files live. It does not scale.
The part that trips people up
- SAN versus NAS. Both are storage on a network. A NAS shares folders (file-level, using SMB or NFS). A SAN presents raw disks (block-level, using iSCSI or Fibre Channel). If the question says "block-level" or "appears as a local disk," it is a SAN.
- MAN versus WAN. Both leave the building. If it stays inside one city, MAN. If it spans cities or countries over carrier links, WAN.
- WAN does not mean internet. A private WAN can be leased lines that never touch the internet.
How the exam asks it
- "Offices in three states connected by carrier circuits" means WAN.
- "Bluetooth between a watch and a phone" means PAN.
- "Manage accounts and backups from one place" means client-server.
- "Each user shares from their own PC, security is inconsistent" means peer-to-peer.
- "Servers access disk arrays as if local, over iSCSI" means SAN.
What to memorize
- Reach, smallest to largest: PAN, LAN, MAN, WAN.
- SAN is storage, not distance.
- Client-server centralizes. Peer-to-peer does not scale.