IoT Gateways and Device Connectivity
What the exam tests
This domain covers gateway roles and how devices attach to networks: southbound device protocols, northbound backhaul, onboarding, and selection criteria.
Core rules
- A gateway bridges southbound device networks (ZigBee, Modbus, BLE, sub-GHz) to northbound IP, cellular, or Ethernet.
- Functions include protocol translation, device management proxy, local rules, buffering during outages, and security termination.
- Onboarding methods include pre-provisioned credentials, registration codes, and zero-touch bootstrap; choose based on scale and trust.
- Connectivity selection: Wi-Fi for high throughput and mains power; cellular for wide-area mobility; LPWAN for low power and small payloads; wired for determinism.
Worked example
A factory has 200 Modbus RTU sensors and needs cloud analytics, but the OT network must not be exposed. Choose an industrial gateway with two serial ports, Modbus polling, local filtering, and a cellular backhaul with TLS. Reasoning: Modbus is not IP-routable, so translation is mandatory; local filtering cuts uplink cost; cellular avoids touching the IT firewall; TLS protects the WAN. The gateway should buffer data when the link drops.
Traps
- A router forwards IP packets; a gateway may also translate non-IP protocols and apply device-level policy.
- Assuming a gateway is always required; IP-native devices can connect directly to the platform.
- Ignoring northbound bandwidth and power; a gateway that polls every second can overwhelm a metered link.