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Quiz: Wireless Communication with the Pico W

Test your understanding of wireless communication with the Pico W with these review questions.

1. What is DHCP?

  1. A labeled channel that groups related MQTT messages together
  2. The human-readable name of a Wi-Fi network
  3. The process a router uses to automatically hand out a network address to each new device
  4. A numeric label that uniquely identifies a device on a network
Show Answer

The correct answer is C. DHCP (Dynamic Host Configuration Protocol) is the process a router uses to automatically hand out a network address to each new device, rather than requiring a person to type one in by hand. Option A describes an MQTT topic, option B describes a network SSID, and option D describes the IP address DHCP actually assigns — related, but not DHCP itself.

Concept Tested: DHCP

2. What is an MQTT broker?

  1. A device that scans for advertisements and initiates a BLE connection
  2. A program that listens for incoming HTTP requests and sends back HTTP responses
  3. A small web page automatically served to anyone who joins a device's network
  4. A server that receives messages from devices and forwards them to any other device that has subscribed to receive them
Show Answer

The correct answer is D. An MQTT broker is a server that receives messages from publishing devices and forwards them to any other device that has subscribed to receive them, acting as the middleman so no device ever contacts another device directly. Option A describes a BLE central, option B describes a web server, and option C describes a captive portal.

Concept Tested: MQTT Broker

3. How does access point mode differ from station mode on a Pico W's Wi-Fi radio?

  1. Station mode creates a new network for other devices to join, while access point mode joins an existing network created by a router
  2. Access point mode creates its own network that other devices can join directly, while station mode joins an existing network created by a router
  3. Station mode and access point mode are two names for the exact same behavior
  4. Access point mode can only be used with Bluetooth Low Energy, not Wi-Fi
Show Answer

The correct answer is B. Access point mode flips the familiar arrangement around: the Pico W creates its own network that other devices can join directly, useful when there's no existing Wi-Fi available, while station mode is the familiar role of joining an existing network created by a router. Option A reverses these roles. Option C incorrectly treats them as identical, and option D is false since access point mode is a Wi-Fi feature, not a Bluetooth one.

Concept Tested: Access Point Mode

4. Based on the chapter's comparison table, which scenario best fits MQTT rather than HTTP?

  1. A robot streaming frequent small sensor updates to multiple listening dashboards
  2. A phone's browser checking a robot's status page once
  3. A one-time file download from a web server
  4. A device requesting a single specific piece of data on demand
Show Answer

The correct answer is A. The chapter's comparison table lists MQTT's best fit as "frequent small updates broadcast to multiple listeners," exactly matching a robot streaming sensor updates continuously. Options B, C, and D all describe one-off, on-demand exchanges of a specific piece of data, which the table identifies as HTTP's strength instead.

Concept Tested: MQTT Protocol

5. What is the difference between a BLE peripheral and a BLE central?

  1. A peripheral scans for advertisements and initiates connections, while a central advertises and waits to be connected to
  2. A peripheral and a central both advertise simultaneously and connect to whichever responds first
  3. A peripheral is the device being connected to, typically advertising and waiting, while a central scans for advertisements and initiates the connection
  4. A peripheral can only send data, while a central can only receive data
Show Answer

The correct answer is C. A BLE peripheral is the device being connected to — it advertises, then waits, and typically has limited power, like a sensor or robot — while a BLE central is the device that scans for advertisements and initiates the connection, typically a phone or computer. Option A reverses these roles. Option B misdescribes the advertising process, and option D incorrectly restricts data direction, which characteristics can support in either direction.

Concept Tested: BLE Peripheral

6. A student's robot needs to broadcast its distance-sensor reading once per second to any dashboard that wants to watch, without knowing in advance how many dashboards will be listening. Which communication approach from this chapter best fits this need?

  1. A one-time HTTP GET request sent to each dashboard's IP address
  2. BLE pairing, since dashboards must be paired individually before receiving any data
  3. A captive portal displayed to each dashboard on first connection
  4. MQTT publish-subscribe, publishing the reading to a topic that any number of dashboards can subscribe to
Show Answer

The correct answer is D. MQTT's publish-subscribe model lets one device publish a message to a topic, and any number of subscribing devices receive a copy, without the publisher needing to know who or how many devices are listening — exactly matching this scenario. Option A requires knowing every dashboard's address in advance, option B misapplies BLE pairing to what is really a Wi-Fi/MQTT scenario, and option C misapplies a captive portal, which is for initial Wi-Fi setup, not ongoing data streaming.

Concept Tested: Publish Subscribe Model

7. A student is designing a BLE-based robot and wants a central device (like a phone) to be able to read and write the robot's left motor speed as an individual value. Which BLE structure should represent "left motor speed"?

  1. A BLE characteristic
  2. A BLE service
  3. A BLE advertisement
  4. The pairing process
Show Answer

The correct answer is A. A BLE characteristic is an individual piece of data or a controllable value, such as "left motor speed," that a central device can read, write, or subscribe to for updates — exactly matching the chapter's own example. A BLE service (option B) is a named collection of related characteristics, not a single value. A BLE advertisement (option C) only announces a device's presence before connection, and pairing (option D) establishes trust, not individual data values.

Concept Tested: BLE Characteristic

8. A student controls a robot wirelessly and sends a "stop" command when the robot is 5 cm from a wall. The robot travels several additional centimeters before actually stopping. Based on this chapter, what is the most likely explanation?

  1. The robot's MQTT topic name was misspelled
  2. The robot's BLE characteristic was never paired
  3. Network latency delayed the stop command's arrival, so the robot kept moving during that delay before reacting
  4. The robot's IP address changed mid-transmission
Show Answer

The correct answer is C. The chapter explicitly warns that network latency is the delay between sending a message and it arriving, and that a robot waiting on a delayed "stop" command can travel farther than expected before it reacts — exactly the scenario described. A misspelled topic (option A) or a missing pairing (option B) would typically prevent the command from arriving at all rather than just delaying it, and option D describes an unrelated addressing issue.

Concept Tested: Network Latency

9. A robot responds instantly to wireless commands near its access point but becomes unreliable and eventually stops responding entirely as a student walks it farther away, especially through walls. What does the chapter identify as the most likely explanation?

  1. The MQTT broker automatically disconnects devices after a fixed number of messages
  2. The robot has exceeded its wireless range, where the signal has become too weak to maintain a reliable connection
  3. The robot's DHCP-assigned IP address expires after a fixed distance
  4. Station mode only functions within one meter of the access point
Show Answer

The correct answer is B. Wireless range is the maximum distance a device can move from its access point or peer before the signal becomes too weak to maintain a reliable connection, and the chapter notes that walls, metal objects, and other wireless devices can shrink it well below its advertised maximum — exactly matching the described degradation with distance and walls. Options A, C, and D all invent distance-based failures that the chapter does not describe for those specific mechanisms.

Concept Tested: Wireless Range

10. A student deploys the chapter's simple Pico W web server example and exposes it directly to the open internet so they can control their robot from anywhere. What does the chapter's guidance say about this decision?

  1. This is safe as long as the robot uses HTTP rather than MQTT
  2. Exposing a web server to the internet is only a risk if BLE is also enabled
  3. REST endpoints are automatically encrypted, so exposure to the internet carries no risk
  4. The tiny web server has no security at all, and should be kept on a trusted local network rather than exposed to the public internet without adding authentication first
Show Answer

The correct answer is D. The chapter's explicit warning states that the tiny web server example has no security at all, and that it's fine for a classroom demo on a trusted network but should never be exposed directly to the open internet without adding authentication first. Options A, B, and C each falsely claim some form of built-in safety that the chapter directly contradicts.

Concept Tested: Network Security