AWS IoT Device Defender now supports monitoring of device disconnect durations

AWS IoT Device Defender Rules Detect now supports a new disconnect duration metric to monitor the duration of disconnect of each device. With this additional metric, you can track how long a device has been disconnected to learn whether it is operating as expected. You can also configure alarms at predefined threshold levels and be alerted in the case of persistent device connectivity issues. Reliable connectivity is fundamental for the effective functioning of any IoT solution. However, there are many reasons where connectivity can be impaired and cause interruptions to device operations. With the new disconnect duration metric, you can more easily monitor active connection status across your fleet, be notified when devices are disconnected for longer than a predefined duration, perform targeted troubleshooting, and assess potential security implications. Anomalous devices detected with this metric can also be queried and targeted using Fleet Indexing within [AWS IoT Device Management](https://aws.amazon.com/iot-device-management/) and perform over-the-air updates or other mitigation actions using Jobs. The disconnect duration metric is available through the AWS IoT Console and AWS CLI. This metric is also supported by the [ListMetricValues API](https://docs.aws.amazon.com/iot/latest/apireference/API%5FListMetricValues.html) so you can write specific queries, such as identifying total disconnected time of a device. For a step-by-step guide on how to get started with disconnect duration metric, please visit this [blog](https://aws.amazon.com/blogs/iot/how-to-get-started-with-the-new-disconnected-duration-metric-in-aws-iot-device-defender/). For additional documentation, see [Cloud-side metrics](https://docs.aws.amazon.com/iot/latest/developerguide/detect-cloud-side-metrics.html#detect-disconnect-duration) in the AWS IoT Device Defender Developer Guide. Disconnect duration metric is available in all [AWS Regions](https://aws.amazon.com/about-aws/global-infrastructure/regional-product-services/) where AWS IoT Device Defender is available. For more information on AWS IoT Device Defender, please visit the [website](https://aws.amazon.com/iot-device-defender/).