Board exam: Unit 1 carries 11 marks — MCQ + short + long questions. Every section ends with exam-style practice.
1.1
Concept of Telecommunication
Define telecommunication, broadband, bandwidth, throughputCompare 3G, 4G and 5G mobile generationsExplain data packets, frequency and communication modes
🎯 Problem of the day
Ramesh's family pays for "100 Mbps fiber" but his speed test in his room shows only 23 Mbps. Is the ISP cheating? By the end of this section, you will be able to judge.
1.1 · Key termWhat is Telecommunication?
Tele (Greek: far) + communicare (Latin: share)
Sending & receiving information over long distances electronically
Devices: telephone, mobile, radio, TV, computer
Examples: phone call, SMS, watching a TV program
Your grandparents' era: letters took 2 weeks. What changed the world faster — roads or telecommunication? Why?
1.1 · Key termBroadband — the fast highway to the Internet
High-speed Internet carrying large data quickly
Far faster than old dial-up telephone Internet
Enables video classes, streaming, gaming, big downloads
Used in homes, schools, offices, public places
Which broadband type does YOUR home or school use? How could you find out today?
1.1 · Key termBandwidth — how wide is the road?
Maximum data a network can carry per second
Like the number of lanes on a highway
Measured in bps, Kbps, Mbps, Gbps
More bandwidth → smoother streaming, faster downloads
If a highway has 8 lanes but a traffic jam, do cars still move fast? (Hint: this leads to our next term!)
1.1 · Key termThroughput — the real speed you get
Actual data successfully delivered per second
Always ≤ bandwidth — traffic, distance, interference reduce it
Measured in bps, Mbps, Gbps (same units)
Speed-test apps measure throughput, not bandwidth
Design an experiment: how would you prove throughput drops as you walk away from the router?
1.1 · Mobile generations3G → 4G → 5G: the evolution
3G · 3rd Generation
Mobile Internet became practical
Video calls, MMS, mobile apps
Speed: up to a few Mbps
4G · LTE
Fast download/upload, HD streaming
Low latency (less delay)
Smooth gaming, cloud apps
5G · 5th Generation
Super-fast, near-zero delay
AR/VR, self-driving cars, IoT
Millions of devices per area
Nepal Telecom & Ncell run 4G nationwide; 5G is being tested. What would 5G change for a farmer in Jumla? A doctor in Kathmandu?
1.1 · Core ideaData Packets — messages travel in pieces
Big data is broken into small packets before sending
Each packet carries sender & receiver address
Packets may take different routes, then reassemble
Result: faster, reliable, efficient long-distance transfer
Analogy: moving a house through a narrow door — brick by brick, each labeled. Why is labeling (addresses) essential?
1.1 · Key termFrequency — how often signals vibrate
Section 1.1 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.2
Communication Channel / Media
Distinguish guided (wired) from unguided (wireless) mediaDescribe CAT6 and optical fiber cablesExplain Wi-Fi, Bluetooth, RFID and satellite communication
🎯 Problem of the day
Your school gets budget for Internet in 2 buildings, 300 m apart, crossing a road. Cable or wireless? Copper or fiber? Every choice costs differently — let's learn enough to advise the principal.
1.2 · The big splitGuided vs Unguided media
Communication media = path carrying data between devices
TV, weather, GPS, military, Internet in remote areas
After the 2015 earthquake, phone towers failed but satellite phones worked. Why? What does this teach about network design?
1.2 · Compare & contrastGuided vs Unguided — head to head
Guided (wired)
Unguided (wireless)
Data travels through wires/cables
Data travels through air, no wires
Not affected by rain or wind
Weather can weaken signals
Best for nearby devices (LAN)
Best for distant devices (WAN)
Fixed path for data
No fixed path — travels freely
e.g. CAT6, coaxial, optical fiber
e.g. Wi-Fi, Bluetooth, microwave, satellite
Back to the school problem: 2 buildings, 300 m, road in between. Argue for fiber underground vs wireless bridge — cost, speed, digging, permission!
Section 1.2 · Exam practice🎯 MCQ Drill — Communication Media
Section 1.2 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.3
Connectors
Identify the RJ45 connector and its purposeExplain what a media converter does and when it is needed
🎯 Problem of the day
The ISP's fiber reaches your school gate, but your computers only have copper Ethernet ports. Two small, cheap devices bridge this world of glass and copper. Meet them now.
1.3 · ConnectorRJ45 — the click you know
Registered Jack 45 — standard Ethernet connector
8 pins in a modular jack format
Easy click-in insertion & removal, standard wiring schemes
Reliable high-speed data over Ethernet networks
Find an RJ45 port in your school today. Photograph 3 different devices that have one.
Section 1.3 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.4
Networking Devices
Explain repeater, hub, switch, bridge and routerChoose the right device for a given networking problem
🎯 Problem of the day
Five gadgets sit in a dusty server rack. One boosts, one shouts to everyone, one whispers to the right PC, one joins twins, one finds the best road across the world. Can you match names to jobs by the end?
1.4 · Device 1Repeater — the signal booster
Accepts weak signals, regenerates them fresh & strong
Enables long-distance data transfer
Works at signal level — does not read addresses
Real life: Wi-Fi range extenders in big houses
CAT6 fades after 100 m. Where exactly would you place repeaters on a 250 m cable run?
1.4 · Device 2 vs 3Hub vs Switch — shouting vs whispering
Hub: multi-port box; copies data to every computer
Cheap, simple, connects star topology — now outdated
Switch: learns addresses; sends data only to target
Faster, less traffic, more secure — replaced hubs
Hub = teacher announcing to whole class. Switch = passing a private note. Which leaks secrets? Which wastes time?
1.4 · Device 4Bridge — joining twin networks
Interconnects two networks with similar protocols
Inspects incoming signals: forward or discard?
Reduces unnecessary traffic between segments
Like a checkpoint between two similar neighbourhoods
Bridge vs switch — both filter by address. What key difference remains? (Hint: how many networks vs how many devices?)
1.4 · Device 5Router — the intelligent path-finder
Joins multiple networks, wired or wireless
Works using IP addresses
Intelligent: picks the best possible path for data
Your home "Wi-Fi box" is a router + more
Google Maps reroutes you around a traffic jam. Routers do the same for packets. What "jams" exist on the Internet?
1.4 · Master tableFive devices — one glance
Device
Main job
Smartness
Everyday analogy
Repeater
Regenerates weak signals for distance
None — just boosts
Megaphone relay
Hub
Connects PCs; copies data to all ports
None — broadcasts
Loudspeaker announcement
Switch
Connects PCs; sends only to target
Learns device addresses
Postman with names
Bridge
Joins two similar networks; filters
Forward or discard
Border checkpoint
Router
Joins different networks; best path
IP-based path finding
GPS navigator
Field visit (Book Activity 1.1): visit an ISP/school lab, photograph each device, label its cables. Which did you find most of?
Section 1.4 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.5
Network Topologies
Describe bus, star, ring and hybrid topologies with featuresState advantages and disadvantages of computer networksSelect a suitable topology for a given scenario
🎯 Problem of the day
Your school lab has 36 computers to connect. One cheap cable through all? A central switch? A loop? Wrong choice = one loose cable kills the whole lab on exam day. Choose wisely!
1.5 · What is topology?Topology — the network's shape
The connection pattern of network components
Physical: hardware layout · Logical: data's path
LAN topology = cabling structure of local computers
Four mains: bus, star, ring, hybrid
City roads also have topologies: one main road, roundabout hub, ring road. Match each to a network topology!
1.5 · Topology 1Bus — one cable for everyone
All nodes share a single backbone cable
Terminators at both ends absorb signals
Cheap, least cable, easy for small networks
Weakness: backbone cut = whole network down
Like one water pipe serving a whole street — what happens to all houses if the pipe bursts in the middle?
1.5 · Topology 2Star — everyone to the center
All nodes connect to a central hub/switch
Fast performance, low traffic, easy to troubleshoot
One node fails → others keep working
Weakness: central device fails → all down
Star is today's most common LAN topology. Why do schools accept its "single point of failure" risk anyway?
1.5 · Topology 3Ring — pass it around the loop
Each computer connects to the next — closed loop
Data moves sequentially, node to node
All computers have equal responsibility
Handles high traffic well; uses fiber, repeaters for size
A relay race: the baton passes runner to runner. What happens if one runner leaves the track? How could TWO tracks fix it?
1.5 · Topology 4Hybrid — mix and match strengths
Combination of two or more topologies in one network
e.g. star networks per department + bus/ring backbone
Flexible & scalable — grows with the organization
Reduces chance of complete network failure
Nepal's banks: star LANs in each branch, WAN links between cities. Why does almost every real network end up hybrid?
1.5 · The bigger pictureComputer networks — worth it?
Section 1.5 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.6
Networks by Coverage: PAN · LAN · MAN · WAN
Classify networks by geographical coverageState features and examples of PAN, LAN, MAN and WAN
🎯 Problem of the day
Your earbuds, the school lab, Kathmandu's cable TV network and the Internet itself — four networks, four sizes. From 10 metres to the whole planet: let's zoom out step by step.
1.6 · Zoom outFour circles of coverage
PAN: around one person (~10 m)
LAN: a room, building, school (~1 km)
MAN: a city or valley
WAN: countries → the whole world
Trace one WhatsApp message: phone (PAN Bluetooth headset) → home Wi-Fi (LAN) → city ISP (MAN) → world (WAN). Every layer, every day!
1.6 · Smallest firstPAN — the personal bubble
Connects devices around one person, up to ~10 m
Phone ↔ smartwatch, earbuds, laptop, printer
Transfers files, photos, videos between own devices
Easy setup — basic configuration only
Count YOUR PAN right now: how many devices are wirelessly linked around you or a family member?
1.6 · The classicLAN — one building, high speed
Limited to small areas: room, building, school (≤ ~1 km)
Generally wired; wireless version = WLAN
Fastest data transfer of all network types
Low error rate; common topologies: bus, star, ring
Why is LAN faster than MAN and WAN? Think: distance, cable quality, number of hops.
1.6 · City scaleMAN — the metropolitan web
Covers a city, valley or metropolitan area
Bigger than LAN, smaller than WAN; medium speed
Owned by single or multiple organizations
Examples: cable TV networks, city DSL, LAN-to-WAN uplinks
Dish Home cable TV serves the whole valley. Which network type is that? What about WorldLink linking its city offices?
1.6 · Planet scaleWAN — the world-wide giant
Extends over large geographical areas — the largest network
Uses satellites, public carriers, undersea cables
Owned by multiple organizations, not one
Examples: the Internet, 4G mobile broadband, satellite links
WAN has the LOWEST speed yet is the most valuable network. Why do we tolerate its delays?
1.6 · Master tablePAN vs LAN vs MAN vs WAN
PAN
LAN
MAN
WAN
Coverage
~10 m, one person
Room–building, ≤1 km
City / valley
Country → world
Speed
Low–medium
Highest
Medium
Lowest, high delay
Ownership
Individual
One organization
Single/multiple orgs
Multiple orgs
Media
Bluetooth, USB
CAT6, Wi-Fi
Fiber, DSL, wireless
Satellite, public carriers
Example
Phone ↔ earbuds
School lab
Cable TV network
The Internet
Board favourite: "Differentiate LAN and MAN/WAN." Practice writing any 4 rows of this table from memory!
Section 1.6 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.7
Network Architecture & Protocols
Compare client-server and peer-to-peer architecturesState benefits and limitations of eachIdentify 10 key protocols: IP, TCP, HTTP, HTTPS, FTP, SMTP, POP, DNS, DHCP, BGP
🎯 Problem of the day
A restaurant with waiters vs a potluck picnic where everyone shares — two ways to organize people, two ways to organize computers. And like any country, networks need laws. Meet the architectures and their rule-books (protocols).
1.7 · Architecture 1Client-Server — the restaurant model
Powerful server provides services; clients request them
Server = central controller of network resources
OS: Windows Server, Linux (Ubuntu Server), UNIX
Examples: school result server, bank systems, Google
When you open your school's result website, who is the client? Who is the server? What is requested; what is served?
1.7 · Architecture 2Peer-to-Peer — the potluck model
All computers are equal — no central server
Also called a workgroup; each shares own resources
Best for small offices, rooms, buildings
Works on Windows 11, macOS, Ubuntu — built-in support
Group project with no leader: quick to start, but who keeps the master copy? What breaks first as the group grows?
1.7 · Face-offClient-Server vs Peer-to-Peer
Client-Server ✔ / ✘
✔ Centralized backup of all data
✔ Dedicated server → faster resource sharing
✔ Better security — central administration
✘ Costly server + admin needed; server fails → all suffer
Peer-to-Peer ✔ / ✘
✔ Cheap & easy — no server, no admin
✔ One computer's failure doesn't stop others
✔ Each user controls own shared resources
✘ Weak security, scattered data, poor for big networks
A 4-PC stationery shop vs a 200-PC bank: choose the architecture for each and defend with cost, security, scalability.
1.7 · The rule-booksProtocols — languages of the network
Protocol = set of rules for communication between computers
Both sides must "speak" the same protocol
First protocol ever: NCP (Network Control Protocol)
Today's Internet runs on the TCP/IP family
Imagine a phone call where you speak Nepali and they hear only French — that's two devices without a common protocol!
1.7 · Protocol pack 1Moving & addressing data
IP — Internet Protocol
Gives every device a unique address; routes packets to the right destination.
TCP — Transmission Control Protocol
Breaks data into packets, checks delivery, reassembles in order. TCP/IP together run the Internet.
DHCP — Dynamic Host Configuration
Automatically hands out IP addresses when devices join a network — no manual setup.
BGP — Border Gateway Protocol
The Internet's postal system between ISPs: chooses routes between large networks worldwide.
When your phone joins school Wi-Fi and "just works" — which of these four did the silent work first?
Section 1.7 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.8
Concept of IP Addressing
Explain the purpose of IP addressesDescribe IPv4 and IPv6 with their featuresCompare IPv4 and IPv6
🎯 Problem of the day
The world has ~8 billion people but IPv4 offers only 4.3 billion addresses — and we ran out! How does your new phone still get online? A 128-bit hero has the answer.
1.8 · The ideaIP address — every device's home address
IP gives each device a unique address on a network
Routes data so it reaches the correct destination
Like a house address for letters — but for packets
Two versions in use: IPv4 and IPv6
Book Activity 1.2: open Command Prompt, type ipconfig. Find your IPv4 address, subnet mask and default gateway. What might the gateway be?
1.8 · Version 4IPv4 — the classic that ran out
32-bit addresses → ~4.3 billion unique addresses
Dotted-decimal: four numbers, e.g. 192.168.1.1
Address exhaustion: devices outgrew supply
Rescue tricks: NAT & private address ranges
Estimate: phones + laptops + TVs + IoT ≈ 20+ billion devices. 4.3 billion addresses. What HAD to be invented?
1.8 · Version 6IPv6 — an address for every grain of sand
IPv6 was ready in 1998 — why is adoption still slow? (Hint: cost of replacing what already works.)
1.8 · Master tableIPv4 vs IPv6 — board favourite!
IPv4
IPv6
32-bit address length
128-bit address length
Decimal, dotted: 192.168.1.1
Hexadecimal, colons: 2001:0db8:…
~4.29×10⁹ addresses
~3.4×10³⁸ addresses
Manual / DHCP configuration
Auto & renumbering configuration
No built-in encryption/authentication
Encryption & authentication provided
Header 20–60 bytes (variable)
Header 40 bytes (fixed)
End-to-end integrity unachievable
End-to-end integrity achievable
Exam tip: learn any 4 rows perfectly. "Differentiate IPv4 and IPv6" is a recurring board question!
Section 1.8 · Exam practice🎯 MCQ Drill — IP Addressing
Section 1.8 · Exam practice✍️ Short & Long Questions (click to reveal answers)
1.9
Internet · Intranet · Extranet
Define Internet, intranet and extranetCompare the three by access, purpose and securityUse network commands: ping, ipconfig, tracert, nslookup
🎯 Problem of the day
A bank has: a public website for everyone, an internal portal only staff can open, and a secure portal its partner insurance company logs into. Three networks, three doors, three keys. Which is which?
Section 1.9 · Exam practice✍️ Short & Long Questions (click to reveal answers)
🛠
Real-Life Problem Clinic
Apply the whole unit to real situations — the way boards test Application & Higher AbilityMethod: read the case → answer the leading questions YOURSELF → then reveal the solution
🎯 How to use this clinic
Teachers: give each case to a group, let them argue through the leading questions for 5 minutes, then reveal. Students at home: write your answer BEFORE clicking — that's where learning happens.
Problem clinic · Case 1 (Book Case Study 1)🏫 The 36-computer lab
Problem clinic · Case 2 (Book Case Study 2)📶 Wi-Fi dies upstairs
Problem clinic · Case 3 (Book Case Study 3)🏢 Birgunj office: 3G → 5G
Problem clinic · Case 4🏠 Design a home network (board LQ!)
Problem clinic · Case 5🌉 Two buildings, one network
Problem clinic · Case 6🐌 "Our Internet is slow!" — the diagnosis drill
UNIT 1 COMPLETE
You can now explain the Internet 🎓
Remember the first slide? Take out your list of guesses about the message to Sydney — how many did you get right?
✅ Board-exam checklist
□ All full forms (DSL, RFID, CAT6, TCP/IP, IPv6…) □ IPv4 vs IPv6 table □ Guided vs unguided table □ LAN vs MAN □ Client-server vs P2P □ One topology diagram drawn from memory □ All 6 clinic cases attempted