Quizzes- MQTT and Node-Red

In a Publish/Subscribe model how does the publisher know who is subscribing.

MQTT uses

MQTT-SN uses

Each client that connects to a broker must have a unique client id?

When connecting to an MQTT broker you always need a username and password?

An MQTT broker can use any port, but by default it uses port 1883?

MQTT transmits data to and from a broker in which format.

Messages sent to an MQTT broker are encrypted by default?

You can subscribe to multiple topics at once using wild cards?

You must always start your topic hierachy with a / e.g. /topic name?

The Last Will Message is used to:

To Receive a last will message.

The Last will message is sent from?

When you publish a message to a topic with the retained flag set what happens to the message?

To receive a retained message?

To delete a retained message from a broker you must?

When you connect to a broker with clean session flag set to true what Happens?

You connect to a broker with the clean session flag set to false and subscribe to the topic house/sensor1.
You then disconnect and after about 10 minutes you reconnect with the same client. Do you need to Subscribe to the topic house/sensor1 again?

You connect to a broker with the clean session flag set to false, and subscribe to the topic house/sensor1 with QOS 1.You then disconnect, and after about 10 minutes you reconnect with the same client. If another client publishes messages on house/sensor1 with QOS 1 while you are disconnected. What happens when you reconnect?

You connect to a broker with the clean session flag set to false, and subscribe to the topic house/sensor1 with QOS 0.You then disconnect, and after about 10 minutes you reconnect with the same client. If another client publishes messages on house/sensor1 with QOS 1 while you are disconnected. What happens when you reconnect?

Node-Red Runs is a XXXXX Application ?

The default port for administering node-red is?

The default settings file is called?

You start node-red from the command line but it fails to start with the Error Message

Error:Port in Use

What is the most likely cause?

Which of the following statements are true?

What does the following command do?

node-red -s mysettings.js  -p 1889

You are using Node-red on a machine called raspberrypi. What is the name of the flow file created by default.

Besides the flow file node node also creates additional files in the .node-red folder. On a server called raspberrypi you would expect to see th following files:

• flows_raspberrypi.json
• flows_raspberrypi.json.backup
• flows_raspberrypi_cred.json.
• flows_raspberrypi_cred.json.backup

True or False?

To create passwords for the admin interface you need to install the command line admin tools?

True or False?

The dashboard nodes are part of the core nodes and installed by default?

True or False?