Data Communication
Class 12 · Computer Science
4 ideas in Class 12 Computer Science, explained in plain words, with games and quizzes to practise.
Parts and Measures
Part of: Messages on the move
Every exchange needs a sender, a receiver, the message, the medium and agreed rules. Capacity is measured two ways: bandwidth is the frequency range from lowest to highest, counted in hertz, and data rate counts bits per second. Higher bandwidth allows a higher rate.
Why it matters. Measures decide whether a link can carry video calls or just text. Learners who compute rates and ranges choose links wisely and spot why slow links drop data.
Key words
- Sender
- : The device that sends data over the network.
- Medium
- : The path carrying the message to its goal.
- Bandwidth
- : The frequency range a channel offers.
- Data Rate
- : Bits travelling per second on a channel.
- Protocol
- : Agreed rules for reliable exchange.
Try it in two minutes
- Name the five parts of a phone call.
- Compute a small upload rate from pages and seconds.
- Subtract two frequencies to find a bandwidth.
Try at home. Ask your child to time an upload and estimate its bits per second.
Modes and Switching
Part of: Messages on the move
Simplex sends one way only, like a keyboard feeding a computer. Half duplex allows both ways but takes turns, like a walkie-talkie. Full duplex carries both ways at once, like a phone call. For routing, circuit switching books one dedicated path first, while packet switching splits messages into packets that travel freely and reunite later.
Why it matters. Direction rules shape every gadget from remotes to phones, and switching shapes the Internet itself. Learners who sort examples correctly predict what each channel can and cannot do.
Key words
- Simplex
- : One-way communication from sender to receiver.
- Half Duplex
- : Two-way communication taking turns.
- Full Duplex
- : Two-way communication at the same time.
- Circuit Switching
- : Booking one dedicated path before talking.
- Packet Switching
- : Splitting messages into free-travelling packets.
Try it in two minutes
- Sort a remote, a walkie-talkie and a phone call into the three modes.
- Trace one dedicated path with a finger.
- Split a note into slips and send each by a different route.
Try at home. Ask your child to label five home gadgets with their direction mode.
Wired and Wireless Media
Part of: How links carry and rules they follow
Guided media run through cables: twisted pairs are cheap and common in phones and local networks, coaxial shields better for longer runs, and fibre carries light fast over backbones but needs pairs for two-way talk. Unguided media ride the air: radio spreads all around and through walls, microwaves need clear sight lines for satellites, and infrared suits short remote-style links. Bluetooth joins close gadgets while new generations speed up mobiles.
Why it matters. No single link fits all distances and budgets. Learners who match cable and wave to the job avoid costly fibre for a mouse and hopeless infrared through walls.
Key words
- Guided Media
- : Signals travelling through physical cables.
- Unguided Media
- : Signals travelling through air as waves.
- Fibre
- : Glass strands carrying data as light.
- Bluetooth
- : Short-range joining of close gadgets.
Try it in two minutes
- Sort home links into cable and air groups.
- Match a TV remote to its wave family.
- Count how many gadgets join one Bluetooth master.
Try at home. Ask your child to find one cable link and one air link at home.
Protocols
Part of: How links carry and rules they follow
Protocols are shared rules for flow, access and addressing. Web pages ride request-response rules between browser and server. Files move under transfer rules, mail queues under mail rules, and direct links use point-to-point checks. Internet delivery splits messages into packets, addresses each, routes them freely and rebuilds them in order.
Why it matters. Different speeds and networks must still cooperate. Learners who know which protocol does what can explain browsing, mailing and downloads.
Key words
- HTTP
- : Rules fetching web pages for browsers.
- FTP
- : Rules moving files between machines.
- SMTP
- : Rules queuing and delivering email.
- TCP with IP
- : Splitting, addressing and rebuilding packets.
Try it in two minutes
- Open a page and name its request-response pair.
- Queue one imaginary mail and deliver it.
- Split a note into packets and rebuild it.
Try at home. Ask your child to match browsing, mailing and file moves to their protocols.
What your child will practise
- Modes and Switching: Desert Quick Fire (Quick Fire)
- Parts and Measures: Ocean Puzzle (Clue Puzzle)
- Protocols: Space Quick Fire (Quick Fire)
- Wired and Wireless Media: Candy Puzzle (Clue Puzzle)
- Wired and Wireless Media: Ocean Quick Fire (Quick Fire)
- Quiz: Modes and Switching (8 questions)
- Quiz: Parts and Measures (8 questions)
- Quiz: Protocols (8 questions)
- Quiz: Wired and Wireless Media (8 questions)