Wired & Wireless Networks
Compare Ethernet, fibre optic, Wi-Fi and Bluetooth across speed, range, security and cost. Learn which connection type to recommend for any scenario - and why the answer is rarely "just use Wi-Fi".
Wired or Wireless?
A gaming studio employs 40 developers who all complain their builds take too long to upload to the shared server. The office has both Ethernet ports and Wi-Fi. The IT manager checks the logs and finds every developer is on Wi-Fi even though Ethernet ports are available at every desk. She mandates Ethernet-only for all build uploads. Upload time drops by 70%.
Every device on a network needs a physical connection (via cable) or a wireless connection (via radio waves or light). The choice between wired and wireless affects four key factors that appear repeatedly in exam questions: speed, security, range and reliability.
Wired connections send electrical signals (or light pulses) down cables. Wireless connections broadcast radio waves. Understanding what each transmission medium can and cannot do explains all the advantages and disadvantages you need to know.
Ethernet - The Wired Standard
Ethernet is the standard wired networking technology used in virtually all LANs. It transmits data as electrical signals through copper twisted-pair cables, categorised by their specification.
- Fast and reliable - no signal competition or interference
- Secure - data cannot be intercepted wirelessly
- Consistent performance - doesn't drop with distance (within 100m)
- Low latency - important for gaming and video calls
- Cheap and easy to install in most buildings
- Devices must be physically close enough to connect by cable
- Cables create clutter and are inflexible
- Susceptible to electrical interference from nearby power cables
- Range limited to 100 metres without repeaters
- Extremely high bandwidth - supports many simultaneous users
- Immune to electromagnetic interference (EMI) - light is unaffected
- Very low signal loss over long distances
- Highly secure - very difficult to tap without detection
- No risk of electrical short circuits
- Expensive to install - specialist equipment and skills required
- Fragile - glass fibres can break under physical stress
- Difficult to repair if damaged
- Cannot carry electricity - devices need separate power
* Theoretical maximum speeds. Real-world speeds are always lower due to interference, distance, network load and hardware limitations.
Wi-Fi and Bluetooth
Wireless technologies use radio waves instead of cables. They vary enormously in range, speed and purpose - Wi-Fi connects devices to a network; Bluetooth connects devices directly to each other.
- No cables needed - devices can move freely within range
- Easy to connect multiple devices without additional cabling
- Good for portable devices: laptops, phones, tablets
- Covers a reasonable area from a single WAP
- Slower and less reliable than wired connections
- Signal weakens through walls, floors and interference
- Less secure - data transmitted through the air can be intercepted
- Multiple users sharing the same WAP reduces performance
- 2.4 GHz band becomes congested in dense environments (offices)
- No infrastructure needed - devices connect directly to each other
- Very low power consumption - ideal for battery-powered devices
- Automatic pairing once configured
- Works without internet connection or network
- Very short range - typically 10 metres
- Very slow data transfer compared to Wi-Fi or Ethernet
- Can only pair with a limited number of devices at once
- Interference possible on crowded 2.4 GHz spectrum
Factors Affecting Wireless Performance
A common exam question type asks you to explain factors that affect a wireless network's performance. There are six key factors you must know.
Signal strength decreases with distance from the WAP. Further away = slower speeds, more packet loss, more disconnections.
Walls, floors and metal structures absorb and reflect radio waves. Thick concrete walls can significantly weaken a Wi-Fi signal.
Other devices on the same frequency (microwaves, baby monitors, other Wi-Fi networks) disrupt the signal. The 2.4 GHz band is heavily congested.
Multiple devices share the WAP's bandwidth. More connected devices = less bandwidth per device = slower speeds.
The WAP standard (802.11n, 802.11ac, 802.11ax) and the device's NIC determine maximum possible speeds. Older WAPs bottleneck newer devices.
WPA2/WPA3 encryption adds a small processing overhead. Not normally significant in practice but mentioned in some exam mark schemes.
Wireless data travels through the air and can be intercepted by anyone within range with the right equipment. Even with encryption (WPA2/WPA3), a determined attacker can capture and attempt to decrypt packets. Wired connections physically contain the signal within the cable - data cannot be intercepted without physical access to the cable. For high-security environments (banks, government, hospitals), this difference matters significantly.
Connection Advisor
Exam questions describe a scenario and ask you to recommend and justify a connection type. Work through these scenarios to practise matching requirements to the right technology.
Signal Range Map
Click inside the floor plan to place a Wireless Access Point (WAP). The coloured zones show strong, medium and weak signal areas. Toggle walls to see how physical barriers attenuate the signal.
Medium Recommendation Engine
Answer five questions about your scenario and the engine will recommend the best transmission medium with a full justification.
Comparison and Exam Application
| Technology | Speed | Range | Security | Cost | Mobility | Best for |
|---|---|---|---|---|---|---|
| Ethernet | High (1 Gbps) | 100m per segment | High | Low | Fixed position | Desktops, servers, reliable connections |
| Fibre Optic | Very High (400+ Gbps) | Hundreds of km | Very High | High (install) | Fixed | WANs, internet backbone, ISP links |
| Wi-Fi | Medium (varies) | 30-50m indoors | Medium (WPA3) | Medium | Full mobility | Portable devices, public areas |
| Bluetooth | Low (2 Mbps) | 10m | Medium | Very Low | Mobile | Peripherals, wearables, short-range |
An exam answer that says "use Ethernet because it is faster" earns 1 mark. An answer that says "use Ethernet because the server room transfers large files between high-traffic servers and needs consistent 1 Gbps speeds without the interference risk that Wi-Fi introduces - any speed drops affect all users simultaneously" earns full marks. Always link the specific property to the specific scenario requirement.
1. A new secondary school is being built. The architect plans to run Cat6 Ethernet to every classroom, plus install Wi-Fi WAPs in every room. Explain why this dual approach is more sensible than choosing only one connection type.
Wi-Fi in every room: Allows students to bring in laptops, tablets and phones and connect to the network without requiring a wired port. Essential for devices that lack Ethernet ports (many modern laptops and all tablets).
Why dual is better than either alone:
- Ethernet only: students with portable devices cannot connect, limiting learning flexibility.
- Wi-Fi only: heavy-use fixed devices (servers, interactive boards, teacher stations) would compete for shared wireless bandwidth, reducing performance for everyone.
The dual approach maximises both performance (where wired is needed) and flexibility (where wireless is needed) without significant extra cost beyond installing the WAPs themselves.
2. Give three reasons why a large bank would use fibre optic cables rather than Cat6 Ethernet to connect its data centres, even though Cat6 would be significantly cheaper to install.
2. Distance: Cat6 Ethernet is limited to 100 metres before signal degrades significantly and requires repeaters. Data centres may be kilometres apart; fibre optic can transmit over hundreds of kilometres with minimal loss, making it the only viable physical option at scale.
3. EMI immunity: Data centres contain thousands of servers, UPS systems and cooling units that generate electromagnetic interference. Cat6 is susceptible to EMI, which can corrupt data. Fibre transmits light, which is completely unaffected by electromagnetic fields, ensuring data integrity - critical for financial transactions where data corruption is unacceptable.
Also accept: security (fibre is very difficult to tap without detection); lower signal degradation over time.
3. Explain why a Wi-Fi network in a busy coffee shop might feel slower than the same network at 6am with no other customers, even though the internet connection speed is identical.
Channel congestion: In a busy coffee shop area, neighbouring businesses also have Wi-Fi networks broadcasting on the same or overlapping channels. The 2.4 GHz band has only 13 channels (3 non-overlapping in practice), so multiple networks interfere with each other, causing retransmissions and delays.
Physical interference: More people in the space can attenuate (weaken) the Wi-Fi signal slightly, as human bodies absorb radio waves.
At 6am: One or no devices share the WAP, no neighbouring channel congestion and no physical interference - the full bandwidth is available to that one device.
The internet connection itself is identical in both cases - the bottleneck is the local wireless network.
Practice what you've learned
Three levels of worksheet covering wired and wireless connections.