✍ 06: Wireless Networking — Exercises¶
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Practice — try each question first, then expand the answer to check your reasoning.
Work through each question, then click ▶ Show answer to check yourself. Review the notes if you get stuck.
💡 Q1. In a crowded building on 2.4 GHz, which three channels should APs use, and why?¶
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**1, 6, and 11** — the only **non-overlapping** 20 MHz channels in 2.4 GHz, minimizing co-channel/adjacent-channel interference.🔐 Q2. Rank WEP, WPA, WPA2, WPA3 by security, and name the cipher WPA2 uses.¶
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**WPA3 > WPA2 > WPA > WEP** (WEP is broken). **WPA2 uses AES-CCMP.**🔹 Q3. Match the 802.11 amendment to its Wi-Fi name: 802.11n, 802.11ac, 802.11ax.¶
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- 802.11n → **Wi-Fi 4** - 802.11ac → **Wi-Fi 5** - 802.11ax → **Wi-Fi 6 / 6E**🌍 Q4. A company wants each employee to log into Wi-Fi with their own credentials. Personal or Enterprise? What server is required?¶
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**WPA2/WPA3-Enterprise (802.1X)**, which requires a **RADIUS** authentication server so each user authenticates with unique credentials.🔹 Q5. Distinguish BSS, ESS, and SSID.¶
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- **BSS** — one AP + its associated clients (identified by BSSID = the AP's MAC). - **ESS** — multiple APs sharing one SSID over a common backbone (enables roaming). - **SSID** — the network **name** clients connect to.🔹 Q6. Laptops keep connecting to a fake "Corp-WiFi" and leaking credentials. Name the attack and one defense.¶
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An **evil twin** attack. Defenses: **WPA2/WPA3-Enterprise** (server certificate validation), **WIPS** to detect rogue APs, and user awareness.💡 Q7. Why does Wi-Fi use CSMA/CA instead of CSMA/CD?¶
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Stations can't reliably **detect** collisions on the shared radio medium (they can't transmit and listen simultaneously), so Wi-Fi **avoids** collisions (listen, wait, use ACKs) rather than detecting them like wired Ethernet.🔹 Q8. Compare the 2.4 GHz and 5 GHz bands (range, speed, congestion).¶
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- **2.4 GHz** — longer range/better penetration, but slower, few channels, and crowded (microwaves, Bluetooth, cordless phones). - **5 GHz** — shorter range, but faster with many clean channels.🔹 Q9. A dense office has poor Wi-Fi capacity despite strong signal. Give two design changes.¶
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**Lower AP transmit power and add more APs** (smaller cells → less co-channel interference, more capacity), use **5 GHz / band steering**, and enable **Wi-Fi 6 (OFDMA)**. Signal strength isn't the problem — contention/capacity is.❓ Q10. What is a wireless site survey, and what deliverable does it produce?¶
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A measurement of RF conditions (passive/active/predictive) to plan AP placement, channels, and power. It produces a **heat map** of signal strength/coverage, revealing gaps and interference.🔹 Q11. Does hiding the SSID make a network secure? Explain.¶
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**No.** The SSID still appears in client probe requests and can be captured. Real protection comes from **WPA2/WPA3 encryption** — SSID hiding is only minor obscurity.📶 Q12. What does a wireless LAN controller (WLC) provide when managing many APs?¶
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Centralized configuration, **channel/power coordination (RRM)**, fast roaming across an ESS, and unified monitoring for many "thin" APs — instead of configuring each AP by hand.⬅️ Prev: Module 05 · 📚 All Exercises · Next: Module 07 — Cloud & Remote Access ➡️
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