Internet of Things

Connecting, securing, and managing device fleets, and moving their telemetry into the cloud.

AWS IoT Core

Managed message broker that securely connects devices to AWS and routes their data to other services.

  • Devices publish and subscribe to MQTT topics; the broker fans each message out to every subscriber — devices never talk to each other directly
  • Rules Engine filters messages with SQL-like syntax and routes them to 20+ AWS services (Lambda, S3, DynamoDB, SNS, Kinesis) — no servers, no polling
  • Device Shadow is a JSON doc holding last-reported and desired state, so an app can read or command a device that's currently offline
  • Every device authenticates with its own X.509 certificate over mutual TLS; an IoT policy controls which topics it may touch
  • Limits: 128 KB max message payload, 8 KB Device Shadow doc; protocols are MQTT, MQTT over WSS, HTTPS, LoRaWAN

Exam triggers

Phrases and scenarios that point here.

  • "Millions of sensors", "connected devices", "telemetry", "device fleet" → IoT Core
  • Constrained device on a flaky, low-bandwidth network → MQTT, which IoT Core speaks natively
  • Send a command to a device that's intermittently offline → Device Shadow, not a direct call
  • Sensor data must land in S3 / DynamoDB / Lambda with nothing in between → Rules Engine

Not this service

  • Compute must run on the device itself, offline → AWS IoT Greengrass
  • App-to-app messaging with no physical devices → SNS, SQS, or EventBridge

Use cases

  • Cold-chain trucks publishing freezer temperature every 30 seconds — a rule writes every reading to DynamoDB and fires SNS the moment one crosses the threshold
  • City-wide smart electricity meters reporting usage on a schedule, with one managed broker instead of a fleet of servers holding connections open
  • Consumer appliance control: the phone app writes "desired: on" to the Device Shadow, and the air-con picks it up the next time it's on Wi-Fi
  • Factory vibration sensors streaming to one topic, where a rule tees the same data into S3 for history and Lambda for anomaly alerts
  • Delivery-bike GPS trackers publishing position, with the rule filtering to only the ones outside their zone before anything is stored

Commonly confused with

Amazon SNSApplication IntegrationAmazon Kinesis Data StreamsAnalytics

Full notes →

Verified against AWS documentation · 2026-09-09