Explore the essentials of advanced FCM messaging, focusing on topics, device groups, and tokens. This quiz challenges your understanding of subscription models, targeting strategies, and best practices for message delivery using FCM.
Which action allows a device to start receiving messages sent to a specific topic in FCM?
Explanation: Devices need to subscribe to a topic to receive messages sent to that topic. Assigning a device a unique token is required for direct device messaging, not topic-based. Adding devices to a group is used for group messaging, not topics. Registering for broadcast is not an FCM messaging term.
In FCM, what is a typical use for a device token?
Explanation: A device token uniquely identifies a specific device for sending direct messages. Broadcasting to all devices is handled differently, usually with topics. Tokens do not identify topics or synchronize groups. The other options confuse tokens with other FCM features.
If you want to send the same message to multiple devices owned by a single user, which FCM feature should you use?
Explanation: Device group messaging enables you to target a set of devices that belong to one user, such as their phone and tablet. Topic messaging is for broadcasting messages to all users subscribed to a topic. Token merging and broadcast tokens are not correct feature names in FCM.
What is the maximum number of topics a single device can subscribe to at one time in FCM?
Explanation: A device can subscribe to up to 2000 topics, which is a generous limit. Lower numbers like 50, 100, and 500 do not reflect the actual constraint and might mislead about scalability. Selecting the correct limit is important for planning topic-based messaging.
How can an app stop a device from receiving messages sent to a specific topic?
Explanation: Unsubscribing is the correct way to remove a device from a topic so it no longer receives topic messages. Disabling messages deals with local settings and does not alter topic subscriptions. Deleting the device token affects all messaging, not just topics. Blocking topic IDs is not an FCM process.
When might a device's token in FCM be refreshed or rotated automatically?
Explanation: A device token may change if the app is restored from a backup or reinstalled, which helps maintain security. Sending messages to a group, low battery state, or creating new topics do not cause token refreshes. The other options do not impact the unique device token assignment.
Which FCM feature is best suited for sending notifications about a universal event, like a service update, to all interested users?
Explanation: Topic messaging lets you easily broadcast to all users who subscribed to the event topic, making it ideal for shared announcements. Device group messaging targets only a set of devices for one user. Direct token messaging isn't scalable for large, shared audiences. Token exchange is not an FCM messaging mechanism.
A user has two phones and a tablet. Which FCM mechanism ensures they receive a message on all their devices at the same time?
Explanation: By registering all the user’s tokens in a device group, group messaging delivers to all at once. Random topic subscription does not guarantee the devices are connected by user. Messaging just one token will miss the other devices. Broadcasting to all topics lacks user specificity.
What is the purpose of a notification key in FCM device groups?
Explanation: The notification key acts as a unique identifier for a device group, allowing messages to be sent to all devices within. It does not relate to premium topics or encryption. Validation of device tokens is a separate matter and not handled by notification keys.
What should an app typically do when it detects a change in its registration token?
Explanation: When the registration token changes, apps should prompt their servers to update the record, ensuring users continue receiving relevant messages. Resubscribing can help but is often managed automatically. Ignoring token changes can disrupt message delivery. Uninstalling the app is unnecessary and excessive.