Cheat sheet · Class 12 · CBSE · Science Computer Science
Computer Networks cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 12 · Computer Science
Cheat sheet
Chapter 11Computer Networks
PAN < LAN < MAN < WAN by area.
1. Types
| Network | Range |
|---|---|
| PAN | ~10 m (Bluetooth) |
| LAN | building/campus |
| MAN | city |
| WAN | countries (internet) |
2. Devices
| Device | Role |
|---|---|
| Modem | converts digital ↔ analog |
| Hub | broadcasts to all ports |
| Switch | sends to the right device (MAC) |
| Router | connects networks, routes packets (IP) |
| Gateway | connects dissimilar networks |
| Repeater | regenerates weak signals |
| NIC / Wi-Fi card | connects a device to the network |
3. Topologies
- bus
- star
- ring
- mesh
- tree
Star: easy to manage but depends on the central hub.
4. Internet Basics
- IP address identifies a device; MAC address is the hardware ID.
- DNS maps domain names to IP addresses.
- URL: protocol + domain + path.
5. Key Points
- ARPANET (1969) began the internet.
- Packet switching splits data into packets.
- Web ≠ internet.
- IPv6 uses 128-bit addresses.
Remember: PAN/LAN/MAN/WAN | devices | topologies | DNS
Computer Networks: questions and notes
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