IN

2.2 The Internet

Understanding cloud computing, bit streaming, IP addressing, Ethernet, and internet fundamentals

Learning Objectives

By the end of this lesson, you will be able to:

  • Show understanding of cloud computing, including public and private clouds, and explain their benefits and drawbacks
  • Show understanding of bit streaming, including real-time and on-demand methods, and explain the importance of bit rates and broadband speed
  • Show understanding of Ethernet and how collisions are detected and avoided using CSMA/CD
  • Explain the differences between the World Wide Web and the internet
  • Explain the use of IP addresses in data transmission, including IPv4 and IPv6 formats, subnetting, and differences between public/private and static/dynamic addresses
  • Explain how URLs are used to locate resources on the World Wide Web and the role of Domain Name Service (DNS)
  • Understand network address translation (NAT) and its purpose
  • Identify fundamental requirements for connecting to the internet

Key Terms

Cloud Computing

Delivery of computing services (storage, processing, networking) over the internet from a third-party provider

Bit Streaming

Contiguous sequence of digital bits sent over internet requiring high-speed data communication link

Ethernet

Protocol used by many wired LANs (IEEE 802.3 standard) that transmits data in frames using MAC addresses

Internet

Massive network of networks made up of various computers and electronic devices

World Wide Web

Collection of multimedia web pages and documents stored on websites, accessed via URLs

IP Address

Unique address for a device on a network, following TCP/IP protocols

IPv4

32-bit IP addressing system with approximately 4 billion possible addresses

IPv6

128-bit IP addressing system with vastly larger address space than IPv4

Subnetting

Process of dividing a larger network into smaller sub-networks for efficient IP address management

Public IP Address

Unique address assigned by ISP, accessible directly over the internet

Private IP Address

Address assigned by router for internal network use, not directly accessible from internet

URL

Uniform Resource Locator - address used to access websites and web resources

DNS

Domain Name Service - system that converts domain names to IP addresses

CSMA/CD

Carrier Sense Multiple Access with Collision Detection - protocol used in Ethernet to handle collisions

NAT

Network Address Translation - technique that allows private IP addresses to access the internet via a public IP

Cloud Computing

Cloud computing refers to the delivery of computing services, including storage, processing power, networking, databases, and software, over the internet. Instead of owning and maintaining physical hardware and software resources, individuals and organizations can access and utilize these services on-demand from a third-party provider.

Real-Life Example: Google Drive

Think of Google Drive or Microsoft OneDrive:

  • Cloud Storage = Your files stored on Google's servers
  • Access Anywhere = Open files from phone, laptop, or school computer
  • No Local Storage Needed = Don't need USB drives or specific computer
  • Automatic Backup = Files safe even if your device breaks

When you save a document to Google Drive, you're using cloud computing!

Types of Cloud Computing

Public Cloud

Storage where customer and provider are different companies. Services provided over public internet, resources shared among multiple users.

Private Cloud

Storage behind company firewall. Customer and provider operate as single entity. More control and security but less scalable.

Hybrid Cloud

Combination of private and public clouds. Sensitive data on private side, other resources from public cloud.

Cloud Storage: Pros and Cons

Pros of using Cloud Storage Cons of using Cloud Storage
Files can be accessed at any time from any device anywhere in the world provided internet access is available If customer has unstable internet connection, they would have problems accessing or downloading their data
No need for a client to carry an external storage device, or use same computer to store and retrieve information Expensive to pay for high download/upload data transfer limits with customer internet service provider
Provides user with remote back-up of data to aid data loss and disaster recovery Costs can be high if large storage capacity is required
Recovers data if a customer/client has a hard disk or back-up device failure Potential failure of cloud storage company is possible – this poses a risk of loss of all back-up data
Cloud storage can be free for small quantities There could be a limit to the amount of storage unless paid for

Cloud Software

Software applications can be delivered to user's computer on demand using cloud computing services. The cloud provider hosts and manages software applications including maintenance, software upgrades, and security for a monthly fee.

Advantages of Cloud Software:
  • Software is fully tested and doesn't need to reside on user's device
  • User can still use software even if internet connection is lost (data stored locally and synced later)
  • Cloud-based applications can perform tasks on local device (different from web apps needing constant connection)

Cloud Computing Network Visualization

How it works: Your devices connect to a router, which connects to the internet and accesses cloud servers. Data flows between your devices and remote servers where applications and files are stored.

Activity 1: Cloud Storage Scenario

A school is deciding whether to use cloud storage for student documents or continue using local servers. Consider these factors:

  • Students need to access work from home and school
  • The school has 1000 students generating approximately 2GB of data each per year
  • Internet connection at school is reliable but some students have poor home internet
  • Budget is limited for IT infrastructure

Task: 1. List two advantages of cloud storage for this school.
2. List two disadvantages of cloud storage for this school.
3. Would you recommend public or private cloud? Why?

Solution:
  1. Advantages:
    • Students can access work from anywhere (home/school) with internet
    • No need for school to maintain expensive local servers and storage hardware
    • Automatic backups protect against data loss from device failures
  2. Disadvantages:
    • Students with poor home internet may struggle to access files
    • Costs could be high for 2000GB (2TB) of storage
    • Risk if cloud provider has outage or goes out of business
  3. Recommendation: Public cloud would be more cost-effective for a school with budget constraints. Private cloud would be better if handling highly sensitive student data, but is more expensive.

Check Your Understanding: Cloud Computing

Answer
  • [1 mark] Delivery of computing services (storage, processing, networking, databases, software) over the internet
  • [1 mark] Services provided on-demand from a third-party provider instead of owning physical hardware
Answer
Public Cloud:
  • Customer and provider are different companies
  • Services over public internet
  • Resources shared among multiple users
  • More scalable, less expensive
Private Cloud:
  • Behind company firewall
  • Customer and provider operate as single entity
  • More control and security
  • Less scalable, more expensive
Answer
  • [1 mark] Software is fully tested and doesn't need to reside on user's device
  • [1 mark] Can still use software if internet connection is lost (data stored locally and synced later)
  • [Additional] Maintenance, upgrades, and security handled by provider
Answer
  • [1 mark] Combination of private and public clouds
  • [1 mark] Sensitive data kept on private side, other resources from public cloud
  • [Additional] Allows organizations to benefit from both while maintaining security for sensitive data

Bit Streaming

Bit streaming is a contiguous sequence of digital bits sent over the internet that requires a high-speed data communication link (such as fast broadband). Bit streaming often involves very large files (like videos), so files usually undergo data compression before transmission.

Real-Life Example: Netflix/YouTube

When you watch Netflix or YouTube:

  • Bit Streaming = Video data sent as continuous sequence of bits
  • Buffer = Temporary storage that collects data before playing
  • Compression = Video files compressed to reduce size
  • On-Demand = You choose when to watch (Netflix)
  • Real-Time = Live streaming (YouTube Live, sports events)

The spinning circle before a video plays is the buffer filling up!

How Bit Streaming Works

  • Sequence of bits transmitted continuously over a single channel
  • Bits transmitted serially, one after another
  • Videos stored on media server
  • During downloading, server sends data to client computer in a buffer
  • Software (media player) receives bit stream from buffer
Role of Buffer:

Buffer is a temporary storage area. Data transmission rate from server to buffer must be greater than rate from buffer to media player. Larger buffer gives better control over bit rate.

Buffer Visualization for Bit Streaming

Low Water Mark
High Water Mark

Buffer Operation: The media player checks that data lies between minimum (low water mark) and maximum (high water mark) values. If buffer drops too low, video pauses. If it gets too full, excess data may be discarded.

Types of Bit Streaming

On-Demand Bit Streaming

  • Digital/analog videos converted to bit streaming format (encoding)
  • Encoded files stored on a server
  • URL of encoded video placed on web server
  • User clicks URL and video downloads as contiguous bit stream
  • Broadcast to user as and when required
  • Possible to pause, rewind, fast forward
Examples:

Netflix, YouTube videos, Amazon Prime Video

Real-Time Bit Streaming

  • Transmits digital data in continuous stream without storing on server
  • Event captured by camera and microphone, sent to computer
  • Video signal encoded to streaming media file
  • Encoded file uploaded to dedicated video streaming server
  • Server sends encoded live video to user's device
  • Cannot pause, rewind, or fast forward (live footage)
Examples:

Live sports events, news broadcasts, video conferencing

Importance of Bit Rates & Broadband Speed

Bit Rate

Number of bits transmitted per second. Media should be delivered at same speed as creation. Transmission to buffer limited by network bandwidth.

Bit Rate Formula:

Frequency × bit depth × channels = bit rate
Example: 44,100 samples/sec × 16 bits/sample × 2 channels = 1,411,200 bps (1,411.2 kbps)

Baud Rate

Number of signal units transmitted per second. One signal unit can represent one or more bits.

Key Point:

Essential to have buffer size sufficiently large so it never gets completely filled or empty during streaming.

Pros of Bit Streaming Cons of Bit Streaming
No need to wait for whole video/music file to download before watching/listening Cannot stream if broadband connection is lost
No need to store large files on your device Security risks associated with downloading files from internet
Allows video/music files to be played on demand (as required) Streaming uses up a lot of bandwidth
No need for any specialist hardware Video files will pause if insufficient buffer capacity or slow broadband
Affords piracy protection (more difficult to copy streamed files than files on hard drive)

Activity 2: Bit Rate Calculation

Calculate the bit rate and file size for these audio scenarios:

  1. Audio CD quality: 44,100 samples per second, 16-bit depth, 2 channels (stereo)
    Calculate bit rate in kbps and file size for a 4-minute song in MB.
  2. Lower quality audio: 22,050 samples per second, 8-bit depth, 1 channel (mono)
    Calculate bit rate in kbps and file size for a 3-minute podcast in MB.

Formula: Bit rate = Frequency × bit depth × channels
File size (bits) = Bit rate × time (seconds)
1 byte = 8 bits, 1 MB = 1,048,576 bytes

Solution:
  1. Audio CD:
    Bit rate = 44,100 × 16 × 2 = 1,411,200 bps = 1,411.2 kbps
    4 minutes = 240 seconds
    File size (bits) = 1,411,200 × 240 = 338,688,000 bits
    File size (bytes) = 338,688,000 ÷ 8 = 42,336,000 bytes
    File size (MB) = 42,336,000 ÷ 1,048,576 = 40.37 MB
  2. Lower quality:
    Bit rate = 22,050 × 8 × 1 = 176,400 bps = 176.4 kbps
    3 minutes = 180 seconds
    File size (bits) = 176,400 × 180 = 31,752,000 bits
    File size (bytes) = 31,752,000 ÷ 8 = 3,969,000 bytes
    File size (MB) = 3,969,000 ÷ 1,048,576 = 3.79 MB

Check Your Understanding: Bit Streaming

Answer
  • [1 mark] Contiguous sequence of digital bits sent over the internet
  • [1 mark] Requires high-speed data communication link (fast broadband)
  • [Additional] Often involves large files that undergo data compression before transmission
Answer
  • [1 mark] Buffer is a temporary storage area on the computer
  • [1 mark] Data transmission rate from server to buffer must be greater than rate from buffer to media player
  • [1 mark] Media player checks data lies between minimum (low water mark) and maximum (high water mark) values
  • [Additional] Larger buffer gives better control over bit rate being sent to media player
Answer
On-Demand:
  • Pre-recorded content
  • Can pause, rewind, fast forward
  • Stored on server
  • Examples: Netflix, YouTube videos
Real-Time:
  • Live content
  • Cannot pause, rewind, fast forward
  • Not stored on server
  • Examples: Live sports, video calls
Answer
  • [1 mark] Transmission rate to buffer is limited by bandwidth of network connection
  • [1 mark] Slow broadband causes buffer to empty, resulting in video pausing
  • [Additional] Higher bit rates (for better quality) require faster broadband speeds
Answer
  • [1 mark] Bit rate = Frequency × bit depth × channels
  • [1 mark] Example: 44,100 samples/sec × 16 bits/sample × 2 channels = 1,411,200 bps
  • [Additional] Frequency = samples per second, bit depth = bits per sample, channels = mono (1) or stereo (2)

Internet vs World Wide Web & Connectivity

Many people confuse the Internet with the World Wide Web (WWW), but they are different concepts. Understanding this difference is fundamental to computer science.

Internet World Wide Web (WWW)
Massive network of networks made up of various computers and electronic devices Collection of multimedia web pages and documents stored on websites
Stands for "interconnected network" Uniform Resource Locators (URLs) specify location of all web pages
Uses Transmission Control Protocol/Internet Protocol (TCP/IP) Web resources accessed by web browsers
The physical infrastructure (cables, routers, servers) Uses the internet to access information from servers and computers

Real-Life Analogy: Roads vs Delivery Service

Internet = Road Network
  • Physical infrastructure (roads, highways)
  • Allows vehicles (data) to travel
  • Rules of the road (TCP/IP protocols)
  • Can carry different types of traffic
WWW = Delivery Service
  • Service that uses roads
  • Delivers specific packages (web pages)
  • Address system (URLs)
  • Needs vehicles (browsers) to operate

Just as delivery services use roads but aren't the same as roads, the WWW uses the internet but isn't the internet itself.

Fundamental Requirements for Connecting to Internet

Device

Computer, tablet, mobile phone

Connection

Telephone line or mobile network (wireless router for tablets/phones)

Router & Modem

Wired or wireless devices to connect to ISP

ISP

Internet Service Provider (hardware and software combination)

Web Browser

Software to access web pages (Chrome, Firefox, Safari, Edge)

Network Evolution: Copper to Fibre Optic

Telephone lines have evolved from copper cables to fibre optic cables:

Copper Cables
  • Limited bandwidth
  • Slower data transfer rates
  • Risk of data corruption from interference
  • Maximum ~100 Mbps
Fibre Optic Cables
  • Greater bandwidth
  • Faster data transfer rates (Gbps)
  • Less risk of data corruption
  • No electrical interference

Fibre optic networks enable fast broadband, allowing telephone and video calls using computers and internet (VoIP - Voice over Internet Protocol).

Voice over Internet Protocol (VoIP)

When using internet to make phone calls, user's voice is converted to digital packages using VoIP:

  1. Voice converted to digital data
  2. Data split into packets (packet switching)
  3. Packets sent over network via fastest route
  4. Packets reassembled at destination
  5. Digital data converted back to voice
Examples:

Skype, Zoom, WhatsApp calls, Microsoft Teams voice calls

Activity 3: Internet Connectivity Setup

A family is setting up internet in their new home. They have:

  • 2 laptops, 3 smartphones, 1 tablet, 1 smart TV
  • Existing telephone line connection
  • Need to access online classes, streaming, and work from home
  • Budget is limited but need reliable connection

Task: 1. List the five fundamental requirements they need for internet connectivity.
2. Would you recommend copper or fibre optic connection? Why?
3. What type of router would be most suitable (wired/wireless)?
4. How many devices can connect simultaneously with a typical home setup?

Solution:
  1. Five requirements:
    • Devices (laptops, smartphones, tablet, smart TV)
    • Telephone line connection
    • Router and modem
    • Internet Service Provider (ISP)
    • Web browser software on devices
  2. Fibre optic recommended because:
    • Faster speeds needed for online classes + streaming + work
    • Multiple devices will be using bandwidth simultaneously
    • More reliable with less interference
    • Future-proof for increasing internet demands
  3. Wireless router - Most suitable as it allows all devices (especially mobile ones) to connect without cables. Could have some wired ports for devices that benefit from more stable connection (like smart TV or work laptop).
  4. Most home routers support 10-50+ devices simultaneously, though performance decreases with more active devices. 7 devices should work fine on a decent home router.

Check Your Understanding: Internet vs WWW

Answer
Internet:
  • Massive network of networks
  • Physical infrastructure
  • Uses TCP/IP protocols
  • Connects computers/devices
World Wide Web:
  • Collection of web pages/documents
  • Uses URLs to locate pages
  • Accessed via web browsers
  • Uses internet to access information
Answer
  • [1 mark] Device (computer, tablet, mobile phone)
  • [1 mark] Telephone line or mobile network connection
  • [1 mark] Router and modem (wired or wireless)
  • [Additional] Internet Service Provider (ISP), Web browser software
Answer
  • [1 mark] Greater bandwidth capacity
  • [1 mark] Faster data transfer rates
  • [1 mark] Less risk of data corruption from interference
  • [Additional] Enables fast broadband for VoIP and video calls
Answer
  • [1 mark] Voice over Internet Protocol - technology for making voice calls using internet
  • [1 mark] Converts voice to digital data packets
  • [1 mark] Uses packet switching to send packets via fastest route, reassembles at destination
  • [Additional] Examples: Skype, Zoom, WhatsApp calls

IP Addresses & Subnetting

An IP address is a unique address for a device on a network. The internet is based on TCP/IP protocols, which define rules agreed by senders and receivers on the internet.

IPv4 Addressing

The most common type of addressing on the internet is IPv4, based on 32 bits giving 2³² (approximately 4 billion) possible addresses.

IPv4 Features

  • Made up of network ID and host ID
  • Composed of four integer numbers (0-255 in denary, 00-FF in hex)
  • Each digit stored as one byte (complete IP = 32 bits / 4 bytes)
  • 32 bits split into four groups of 8 bits (0-255 range)
  • Represented by dotted decimal notation (e.g., 254.0.128.77)
  • First part = Network identifier, second part = Host identifier

Real-Life Example: Home Address

Think of an IP address like a home address:

  • Network ID = Street name (e.g., "Main Street")
  • Host ID = House number (e.g., "123")
  • Full Address = "123 Main Street"
  • Postal System = Internet routing system

Just as mail goes to the right street then specific house, data goes to the right network then specific device.

IPv4 Address Classes Visualization

N
N
N
N
N
N
N
N
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
32-bit IPv4 Address: N = Network bits, H = Host bits

IPv4 Classes: Different classes allocate different numbers of bits to network and host portions. Class A for very large networks, Class B for medium, Class C for small networks.

Network Class IPv4 Range Network Bits Host Bits Network Type
A 0.0.0.0 to 127.255.255.255 8 24 Very large
B 128.0.0.0 to 191.255.255.255 16 16 Medium size
C 192.0.0.0 to 223.255.255.255 24 8 Small networks
D 224.0.0.0 to 239.255.255.255 – – Multi-cast
E 240.0.0.0 to 255.255.255.255 – – Experimental

IPv4 Address Examples

Class A: 29.68.0.43

Binary: 00011101 01000100 00000000 00101011

Network ID: 29, Host ID: 68.0.43 (sub-net ID 68.0, host ID 43)

Class B: 128.148.12.14

Binary: 10000000 10010100 00001100 00001110

Network ID: 128.148, Host ID: 12.14 (sub-net ID 12, host ID 14)

Class C: 195.15.25.240

Binary: 11000011 00001111 00011001 11110000

Network ID: 195.15.25, Host ID: 240

CIDR & Subnetting

Classless Inter-Domain Routing (CIDR)

Developed to improve addressing scheme flexibility. Uses a suffix like 192.30.250.00/18 where 18 bits are for netID and 14 bits for hostID.

  • Example: 195.12.6.14/21
  • 21 bits for netID, 11 bits for hostID
  • Allows 2¹¹ = 2048 hosts
  • More flexible than fixed class system

CIDR allows existing Class A, B, or C addresses to be used with suffixes 8, 16, or 24 respectively.

Subnetting

Process of dividing a larger network into smaller sub-networks for more efficient use of IP addresses.

  • Divides LAN into two or more smaller networks
  • More efficient use of hostID by applying structure
  • CIDR is based on subnetting concepts
  • Routers enable communication between subnets
Example Organization:

150 employees, 6 department LANs + head-office LAN. With subnetting, uses only one Class C address instead of seven.

Subnetting Calculation Example

Organization with IP range 194.10.9.0 to 194.10.9.255 (one Class C address):

  • First three bytes: netID (194.10.9)
  • Last byte (256 codes): hostID
  • Solution: Use top 3 bits for LAN codes (8 possible LANs: 000 to 111)
  • Remaining 5 bits for workstation codes (32 workstations per LAN)
  • Total capacity: 8 LANs × 32 workstations = 256 addresses

With 150 workstations, only 106 addresses unused (reasonable for future expansion). Only one netID used instead of seven.

Advantages of Subnetting

  • Useful in organizations with multiple departments (each department can have own subnet)
  • Organizes large networks into smaller, more manageable sub-networks
  • Reduces network traffic, improving network speed
  • Improves network performance by reducing congestion and increasing efficiency
  • Better utilization of IP addresses, reducing waste
  • Helps isolate problems to specific subnets for easier troubleshooting

Public vs Private IP Addresses

Private IP Addresses

  • Assigned by network router to devices
  • Used within private network for secure connections
  • Reserved for internal use behind router/NAT
  • More secure
  • Unique within their network, can be duplicated in other networks
  • NAT required to access internet
Private IP Ranges:
  • Class A: 10.0.0.0 to 10.255.255.255 (16M addresses)
  • Class B: 172.16.0.0 to 172.31.255.255 (1M addresses)
  • Class C: 192.168.0.0 to 192.168.255.255 (65,600 addresses)

Public IP Addresses

  • Assigned by ISP to network router
  • Accessible directly over internet
  • Used by DNS servers, network routers, directly-controlled computers
  • Less secure than private addresses
  • Can be static or dynamic
  • Static used for hosting websites/services
Static vs Dynamic:
  • Static: Fixed, manually assigned, more secure, more expensive
  • Dynamic: Changes periodically, automatically assigned, less secure, cost-effective

Network Address Translation (NAT)

NAT box has one public IP address visible over internet. Internally, devices use private IP addresses from reserved ranges.

  1. User sends packet from computer to server over internet
  2. NAT server swaps private IP for public IP, attaches PORT ID
  3. NAT tracks which computers use which private IPs
  4. When packet returns, NAT swaps public IP back to private IP
  5. Packet sent through LAN to correct computer

NAT allows multiple devices with private IPs to share one public IP address for internet access.

Activity 4: IP Addressing & Subnetting

A company has been allocated the IP address range 192.168.1.0 to 192.168.1.255 (a Class C address). They have:

  • 4 departments: Sales (25 devices), Marketing (18), IT (30), Admin (15)
  • Each department needs its own subnet
  • Need room for 20% growth in each department
  • Must minimize unused IP addresses

Task: 1. What class is this IP address? How many host addresses total?
2. Design a subnetting scheme for the 4 departments.
3. Calculate subnet masks for each department.
4. How many unused addresses will remain?

Solution:
  1. Class C address (starts with 192). Total host addresses = 256 (0-255, but 0 is network address, 255 is broadcast, so 254 usable).
  2. Subnetting scheme with 20% growth:
    • Sales: 25 + 20% = 30 devices → Need 32 addresses (2⁵ = 32)
    • Marketing: 18 + 20% = 22 devices → Need 32 addresses
    • IT: 30 + 20% = 36 devices → Need 64 addresses (2⁶ = 64)
    • Admin: 15 + 20% = 18 devices → Need 32 addresses
    • Total needed: 32+32+64+32 = 160 addresses (fits within 254)
  3. Subnet masks (using CIDR notation):
    • 32 addresses: /27 subnet mask (255.255.255.224) - 5 host bits (2⁵=32)
    • 64 addresses: /26 subnet mask (255.255.255.192) - 6 host bits (2⁶=64)
    • Allocation:
      • Sales: 192.168.1.0/27 (0-31)
      • Marketing: 192.168.1.32/27 (32-63)
      • IT: 192.168.1.64/26 (64-127)
      • Admin: 192.168.1.128/27 (128-159)
  4. Unused addresses: 254 total usable - 160 used = 94 unused addresses (for future expansion, routers, etc.)

Check Your Understanding: IP Addresses

Answer
  • [1 mark] Unique address for a device on a network
  • [1 mark] Internet based on TCP/IP protocols that require IP addresses
  • [1 mark] Allows data to be routed to correct destination device
  • [Additional] Essential for internet communication, similar to postal address for mail delivery
Answer
  • [1 mark] 32 bits total, divided into 4 groups of 8 bits
  • [1 mark] Each group represented as number 0-255 (denary) or 00-FF (hex)
  • [1 mark] Written in dotted decimal notation (e.g., 192.168.1.1)
  • [1 mark] Consists of network ID and host ID portions
  • [Additional] Different classes (A, B, C) allocate different bits to network/host portions
Answer
  • [1 mark] Process of dividing larger network into smaller sub-networks
  • [1 mark] More efficient use of IP addresses by reducing waste
  • [1 mark] Improves network performance and management
  • [Additional] Allows department segmentation, reduces traffic, isolates problems
Answer
Public IP:
  • Assigned by ISP
  • Accessible over internet
  • Used by servers/routers
  • Less secure
  • Unique globally
Private IP:
  • Assigned by router
  • Internal network only
  • Used by devices behind router
  • More secure
  • Can be duplicated in other networks
Answer
  • [1 mark] Network Address Translation - allows private IPs to access internet via public IP
  • [1 mark] NAT swaps private IP for public IP when sending packets to internet
  • [1 mark] Tracks which devices use which private IPs to route returning packets correctly
  • [Additional] Enables multiple devices to share one public IP address

IPv6, Ethernet, DNS & URLs

IPv6 Addressing

IPv6 has been developed to overcome problems associated with IPv4 address exhaustion. IPv6 is the latest version of Internet Protocol (IP) with a 128-bit address space.

IPv6 Format

  • 8 groups of 4 hexadecimal digits, separated by colons (:)
  • Total of 32 hexadecimal digits (128 bits)
  • Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
  • Uses colon hexadecimal notation
  • Broken into 16-bit parts, each represented by 4 hex characters
Zero Compression:

Consecutive zeros replaced by :: (only once per address)
Example: 2001:0db8:0000:0000:0000:0000:0001 → 2001:0db8::1

IPv6 Advantages over IPv4

  • Larger Address Space: 128-bit vs 32-bit, eliminates need for NAT
  • No NAT Required: Removes risk of private IP address collisions
  • Built-in Authentication: Improved security features
  • Efficient Routing: Simplified header format
  • Automatic Configuration: Devices auto-configure unique IPs
  • Multicast Support: Efficient data distribution to multiple devices

IPv6 Address Examples with Zero Compression

IPv6 Address Explanation
68E6:7C48:FFFE:FFFF:3D20:1180:695A:FF01 Full address (no compression)
72E6::CFFE:3D20:1180:295A:FF01 :0000:0000: replaced by ::
6C48:23:FFFE:FFFF:3D20:1180:95A:FF01 Leading zeros omitted (23 instead of 0023)
::192.31.20.46 IPv4 address embedded in IPv6 format

Ethernet

Ethernet is a protocol used by many wired LANs, adopted as IEEE 802.3 standard. It connects computers/devices together, transmitting data in frames using MAC addresses.

Ethernet Network Components

Node

Any device on the LAN (computer, printer, server)

Medium

Path used by LAN devices (twisted pair, coaxial, or fiber cable)

Frame

Data transmitted in frames containing source/destination MAC addresses

Why Ethernet is Preferred

  • Cost-effective: Relatively inexpensive compared to other systems
  • Stable & Reliable: More secure and consistent than Wi-Fi
  • Fast Data Transfer: High-speed connections
  • Simple Maintenance: Easy to install and maintain

MAC vs IP Address: MAC tells who you are (device identifier), IP tells where you are on internet. Both work together to send messages correctly.

CSMA/CD & Collision Detection

Ethernet supports broadcast transmission to all devices on LAN. Risk: two messages using same data channel could collide.

  1. Carrier Sense: Device checks if channel is free before transmitting
  2. Multiple Access: Multiple devices can access the network
  3. Collision Detection: If collision detected (voltage change on cable)
  4. Jam Signal: Device stops transmitting, sends jam signal
  5. Random Backoff: Waits random time before retrying

CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol defines random wait time to prevent repeated collisions.

IP Address Conflict Error

Occurs when devices on same network have same IP address. Without unique IP, cannot connect to network.

  • Most likely on LAN with dynamic IP addresses
  • Can be resolved by restarting router
  • Dynamic IP addresses get re-assigned
  • Ensure unique IP assignment (static or proper DHCP configuration)

URLs & Domain Name Service (DNS)

Uniform Resource Locator (URL)

Web browsers use URLs to access websites. Easier than typing IP addresses like 109.108.158.1.

URL Format:

https://www.example.com/path/filename

Protocol: http or https
Website Address:
  • Domain host (www)
  • Domain name (example)
  • Domain type (.com, .org, .net, .gov)
  • Country code (.uk, .de, .cy) - optional
Path & Filename: /path/filename (specific page/resource)

Domain Name Service (DNS)

DNS gives domain names for internet hosts and finds IP addresses for domain names. Eliminates need to memorize IP addresses.

  • Converts host names (www.example.com) to IP addresses (107.162.140.54)
  • DNS servers contain database of URLs with matching IPs
  • Process called Name Resolution
  • Uses caching to speed up future requests

Example: Typing "www.google.com" → DNS converts to "142.250.185.78" → Your browser connects to Google's servers.

DNS Resolution Process Visualization

Step 1: User types URL
Step 2: Browser asks DNS server 1
Step 3: DNS server 1 checks cache/database
Step 4: If not found, asks DNS server 2
Step 5: DNS server 2 finds IP address
Step 6: IP sent back through chain
Step 7: Browser connects to website

DNS Process Steps: 1. User types URL → 2. Browser asks local DNS server → 3. If not in cache, queries other DNS servers → 4. IP address found and returned → 5. Cached for future → 6. Browser connects to IP → 7. Website loads.

Activity 5: IPv6 & DNS Analysis

Analyze these networking scenarios:

  1. Convert these IPv6 addresses using zero compression:
    • 2001:0db8:0000:0000:0000:ff00:0042:8329
    • fe80:0000:0000:0000:0202:b3ff:fe1e:8329
    • 2001:0db8:0000:0000:0000:0000:0000:0001
  2. A user types "www.schoolportal.edu" into their browser but gets "Site cannot be reached" error. The internet connection is working. What could be the problem and how would DNS help resolve it?
  3. In an Ethernet network with 20 computers, two devices accidentally get assigned the same IP address. What happens and how can this be resolved?
Solution:
  1. IPv6 Zero Compression:
    • 2001:0db8:0000:0000:0000:ff00:0042:8329 → 2001:db8::ff00:42:8329 (Note: leading zeros removed too)
    • fe80:0000:0000:0000:0202:b3ff:fe1e:8329 → fe80::202:b3ff:fe1e:8329
    • 2001:0db8:0000:0000:0000:0000:0000:0001 → 2001:db8::1
  2. DNS Problem:
    • Possible DNS server failure or misconfiguration
    • DNS cannot resolve "www.schoolportal.edu" to an IP address
    • Solution: Check DNS settings, try different DNS server (like Google's 8.8.8.8), or flush DNS cache
    • DNS helps by converting human-readable domain names to IP addresses computers understand
  3. IP Address Conflict:
    • Both devices cannot connect properly to network
    • Network confusion about where to send data
    • Error messages or intermittent connectivity
    • Resolution: Restart router (reassigns dynamic IPs), manually assign unique static IPs, or check DHCP server configuration

Check Your Understanding: IPv6, Ethernet, DNS

Answer
  • [1 mark] Larger address space (128-bit vs 32-bit)
  • [1 mark] No need for NAT, eliminating private IP collisions
  • [1 mark] Built-in authentication and improved security
  • [1 mark] More efficient routing with simplified header
  • [Additional] Automatic configuration, better multicast support
Answer
  • [1 mark] Protocol for wired LANs (IEEE 802.3 standard)
  • [1 mark] Transmits data in frames using MAC addresses
  • [1 mark] Cost-effective, reliable, fast, and easy to maintain
  • [Additional] More stable and secure than wireless alternatives
Answer
  1. [1 mark] Device checks if channel is free before transmitting (Carrier Sense)
  2. [1 mark] If collision detected (voltage change on cable), transmission stops
  3. [1 mark] Jam signal transmitted to notify other devices
  4. [1 mark] Waits random time (backoff) before retrying transmission
Answer
  • [1 mark] Converts domain names (www.example.com) to IP addresses (192.0.2.1)
  • [1 mark] Eliminates need to memorize numerical IP addresses
  • [1 mark] Maintains database of domain names and corresponding IPs
  • [Additional] Uses caching to speed up future requests (name resolution)
Answer
  • [1 mark] Protocol (http:// or https://)
  • [1 mark] Domain host (www)
  • [1 mark] Domain name (name of website)
  • [1 mark] Domain type (.com, .org, .edu) and optional country code
  • [Additional] Path and filename for specific resource
Answer
  • [1 mark] Technique to shorten IPv6 addresses by removing consecutive blocks of zeros
  • [1 mark] Represented by double colon (::), but can only be used once per address
  • [Additional] Example: 2001:0db8:0000:0000:0000:0000:0001 → 2001:db8::1

Key Takeaways

  • Cloud computing delivers services over internet: public clouds (shared resources), private clouds (dedicated, secure), and hybrid clouds (combination).
  • Bit streaming sends continuous sequence of bits for video/audio: on-demand (pause/rewind) and real-time (live, no pausing). Buffer manages data flow between server and player.
  • Internet vs WWW: Internet is network infrastructure; WWW is collection of web pages using internet to share information.
  • IP addresses uniquely identify devices: IPv4 (32-bit, dotted decimal) vs IPv6 (128-bit, hexadecimal with zero compression).
  • Subnetting divides networks for efficient IP management, reducing waste and improving performance.
  • Public IP addresses are internet-facing (assigned by ISP); private IP addresses are for internal networks (assigned by router).
  • Static IPs are fixed (for servers); dynamic IPs change (for most devices).
  • NAT (Network Address Translation) allows private IPs to access internet via public IP.
  • Ethernet is wired LAN protocol using CSMA/CD to detect and handle collisions.
  • URLs (Uniform Resource Locators) specify web resource locations with protocol, domain, path components.
  • DNS (Domain Name Service) converts domain names to IP addresses through name resolution process.
  • Fundamental internet requirements: device, connection, router/modem, ISP, web browser.
  • Fibre optic cables provide faster, more reliable connections than copper cables.
  • VoIP (Voice over Internet Protocol) enables voice calls over internet using packet switching.

Question Bank

Marking Scheme & Answer
Public Cloud:
  • Customer and provider different companies
  • Services over public internet
  • Resources shared among multiple users
  • More scalable, less expensive
  • Less control and security
Private Cloud:
  • Behind company firewall
  • Customer and provider as single entity
  • More control and security
  • Less scalable, more expensive
  • Dedicated resources
Hybrid Cloud:
  • Combination of public and private
  • Sensitive data on private side
  • Other resources from public cloud
  • Balances cost and security
  • Flexible deployment options
Marking Scheme & Answer
  • [1 mark] Buffer is temporary storage area on computer for streaming data
  • [1 mark] Data transmission rate from server to buffer must be greater than rate from buffer to media player
  • [1 mark] Larger buffer provides better control over bit rate being sent to media player
  • [1 mark] Media player checks data level between minimum (low water mark) and maximum (high water mark)
  • [1 mark] Prevents video pausing by ensuring continuous data supply even with network fluctuations
  • [Additional] Essential for smooth playback, especially with variable broadband speeds
Marking Scheme & Answer
IPv4:
  • 32-bit address space
  • Approx. 4 billion addresses
  • Dotted decimal notation (192.168.1.1)
  • Requires NAT for address conservation
  • Separate security protocols needed
  • Classes A, B, C for different network sizes
IPv6:
  • 128-bit address space
  • Vastly more addresses (3.4×10³⁸)
  • Hexadecimal with colons (2001:db8::1)
  • No NAT required
  • Built-in authentication and security
  • Zero compression for address shortening
Marking Scheme & Answer
  • [1 mark] Divides larger network into smaller sub-networks for better management
  • [1 mark] Reduces network traffic by localizing communication within subnets
  • [1 mark] Improves network performance by reducing congestion
  • [1 mark] Allows more efficient use of IP addresses by allocating only needed addresses to each subnet
  • [1 mark] Enables department/organizational segmentation with separate IP ranges
  • [Additional] Facilitates troubleshooting by isolating problems to specific subnets
Marking Scheme & Answer
  1. [1 mark] User types URL (e.g., www.example.com) into web browser
  2. [1 mark] Browser contacts local DNS server with domain name query
  3. [1 mark] If local DNS server doesn't have IP in cache, it queries other DNS servers in hierarchy
  4. [1 mark] Authoritative DNS server for domain returns IP address (e.g., 93.184.216.34)
  5. [1 mark] IP address returned to browser through DNS server chain, cached for future
  6. [1 mark] Browser establishes TCP connection with web server at that IP, downloads and renders webpage
Marking Scheme & Answer
  • [1 mark] CSMA/CD = Carrier Sense Multiple Access with Collision Detection
  • [1 mark] Device checks if network channel is free before transmitting (Carrier Sense)
  • [1 mark] Multiple devices can access network (Multiple Access)
  • [1 mark] If collision detected (voltage change on cable), transmission stops immediately
  • [1 mark] Jam signal sent, then device waits random time (backoff) before retrying
  • [Additional] Prevents repeated collisions by using exponential backoff algorithm
Marking Scheme & Answer
Static IP Address:
  • Fixed address that doesn't change
  • Manually assigned by admin/ISP
  • Used by servers, websites, network devices
  • More secure, easier to track
  • More expensive, requires configuration
  • Constantly accessible for hosting
Dynamic IP Address:
  • Changes periodically (when reconnecting)
  • Automatically assigned by DHCP
  • Used by residential users, small businesses
  • Less secure, harder to track
  • Cost-effective, convenient
  • ISP can reuse addresses
Marking Scheme & Answer
  • [1 mark] NAT = Network Address Translation
  • [1 mark] Allows multiple devices with private IPs to share one public IP for internet access
  • [1 mark] Swaps private IP for public IP when sending packets to internet, attaches PORT ID
  • [1 mark] Tracks connections to route returning packets to correct private device
  • [Additional] Essential for IPv4 address conservation, security through obscurity
Marking Scheme & Answer
  • [1 mark] Device (computer, tablet, mobile phone)
  • [1 mark] Connection (telephone line, mobile network, or wireless router)
  • [1 mark] Router and modem (wired or wireless)
  • [1 mark] Internet Service Provider (ISP) - provides internet access
  • [1 mark] Web browser software to access and display web pages
  • [Additional] For wireless: Wi-Fi adapter; for modern connections: fibre optic infrastructure
Marking Scheme & Answer
On-Demand Streaming:
  • Pre-recorded content
  • Stored on servers
  • Can pause, rewind, fast forward
  • Accessed when user wants
  • Examples: Netflix, YouTube videos
  • Encoded files stored for repeated access
Real-Time Streaming:
  • Live content
  • Not stored on servers
  • Cannot pause, rewind, fast forward
  • Broadcast as event happens
  • Examples: Live sports, video calls
  • Encoded and transmitted immediately
Commonality: Both transmit data as continuous bit streams, require buffers, depend on broadband speed, and use compression for large files.