Resource Cheatsheet
A+ Core 1 2.2: Wireless Networking Protocols
Professor Messer A+ 220-1201 objective 2.2 — 802.11/Wi-Fi naming, frequency bands, channels and bandwidth, Bluetooth and ISM, RFID passive/active tags, and NFC.
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- A+ Core 1
- Detail
- Wireless Networking Protocols
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In one line: Wi-Fi (IEEE 802.11) uses channels within 2.4/5/6 GHz; Bluetooth and Wi-Fi share the unlicensed ISM band; RFID and NFC add short-range identification and payment.
Companion to: Professor Messer, CompTIA A+ 220-1201 Core 1, objective 2.2 (wireless networking protocols). The full version is the Wireless Networking Protocols class notes; the section overview is the Section 2 sheet.
Wi-Fi naming
| 802.11 standard | Wi-Fi name |
|---|---|
| 802.11ac | Wi-Fi 5 |
| 802.11ax | Wi-Fi 6 / 6E (extended) |
| 802.11be | Wi-Fi 7 |
Standardised by the IEEE 802.11 Committee.
Frequency bands
| Band | Spectrum | Bandwidth options | Interference |
|---|---|---|---|
| 2.4 GHz | Limited — 3 non-overlapping 20 MHz channels (1, 6, 11) | Mainly 20 MHz | Highest |
| 5 GHz | Much more | 20 / 40 / 80 / 160 MHz | Lower |
| 6 GHz | The most | 20 / 40 / 80 / 160 MHz | Lowest |
Channel = a simple label for a slice of spectrum. Example: 2.4 GHz channel 6 = 2.437 GHz; 5 GHz channel 44 = 5.220 GHz.
Bandwidth = how much spectrum one connection uses (20/40/80/160 MHz) — more bandwidth, generally more throughput.
Bluetooth
| Feature | Detail |
|---|---|
| Frequency | 2.4 GHz, part of the unlicensed ISM band |
| Range (consumer) | About 10 m |
| Typical use | Personal devices — headsets, speakers |
ISM = Industrial, Scientific, Medical — unlicensed spectrum, no permit needed.
RFID
| Tag type | Power | Range |
|---|---|---|
| Passive | None — powered by the scanner’s signal | Short |
| Active | Own battery | Longer |
How a passive read works: tag unpowered → scanner brought close → scanner’s RF energy powers the tag → scanner reads the ID code → code compared against a database.
Uses: access badges, retail/manufacturing tags, pet identification.
NFC
Builds on RFID, but two-way (RFID is generally one-way).
| Use | Example |
|---|---|
| Payment | Tap phone/watch at a POS terminal |
| Device setup | Passes Bluetooth/Wi-Fi config to a new device |
| Access | Phone instead of a badge |
🔐 Security notes
- 2.4 GHz congestion can mimic a fault — try 5/6 GHz or a channel change before assuming something’s broken.
- ISM is unlicensed for everyone, including rogue APs — verify SSID and authentication before joining.
- Basic RFID/NFC isn’t inherently encrypted — some badges can be cloned; use encrypted/rolling-code tags for sensitive access.
- Bluetooth’s “10 m” is typical, not absolute — directional antennas can extend an attacker’s range. Turn it off when unused; reject unexpected pairing requests.
- NFC’s tiny range helps, but keep payment PIN/biometric on as a second layer.
Practice drills
1. Which 802.11 standard corresponds to Wi-Fi 6E?
802.11ax (extended to 6 GHz).
2. Why does 2.4 GHz suffer more interference than 5 GHz?
It has far less usable spectrum — only three non-overlapping 20 MHz channels.
3. What does channel 6 on 2.4 GHz correspond to in frequency?
2.437 GHz.
4. What band does Bluetooth use, and what family of frequencies is that part of?
2.4 GHz — the unlicensed ISM band.
5. A pet microchip has no battery. How is it read?
It’s a passive RFID tag — the scanner’s radio signal powers it, then reads its ID.
6. A container needs tracking from much farther away than a badge reader can manage. Passive or active tag?
Active — it has its own battery for longer range.
7. What's the key functional difference between RFID and NFC?
RFID is generally one-way (reader scans tag); NFC supports two-way communication.
Key takeaways
- 802.11 (IEEE) = Wi-Fi. 802.11ac/ax/be = Wi-Fi 5/6(E)/7.
- 2.4 GHz: crowded, only 3 non-overlapping channels. 5/6 GHz: far more spectrum and wider bandwidths (up to 160 MHz).
- Channels simplify referring to frequencies; bandwidth is spectrum used per connection.
- Bluetooth: 2.4 GHz, ISM band, ~10 m, personal devices.
- RFID: passive (scanner-powered, short range) vs active (battery, longer range) tags.
- NFC: two-way, short-range — payments, pairing/setup, access.