> For the complete documentation index, see [llms.txt](https://docs.cybus.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cybus.io/2-4-0/broker.md).

# Broker

- [CybusMQ](https://docs.cybus.io/2-4-0/broker/cybusmq.md): The Industrial MQTT Broker.
- [Configuring CybusMQ](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration.md): Features, concepts, and configuration options for CybusMQ.
- [Metadata Store](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/metadata-store.md): The metadata store manages retained messages and subscription data across the CybusMQ broker cluster, ensuring efficient replication and cluster scaling.
- [Clustering Connections](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/clustering-connections.md): CybusMQ clustering connection improvements for reliable message delivery and high throughput between broker nodes.
- [Continuous Cluster Discovery in Kubernetes](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/continuous-cluster-discovery-in-kubernetes.md): CybusMQ continuous cluster discovery in Kubernetes prevents split-brain scenarios through periodic polling of the Kubernetes API.
- [Synchronous SUBSCRIBE Handling](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/synchronous-subscribe-handling.md): CybusMQ synchronous SUBSCRIBE handling ensures the cluster is ready before sending SUBACK, preventing message loss during overload scenarios.
- [Duplicate Message Delivery](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/duplicate-message-delivery.md): Configure duplicate message delivery behavior in CybusMQ.
- [Collocated One-way and Mutual TLS](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/collocated-tls-configuration.md): CybusMQ supports both one-way TLS and mutual TLS clients on the same listener with configurable mount point routing.
- [Self-Refreshing Webhooks Cache](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/self-refreshing-webhooks-cache.md): CybusMQ self-refreshing webhooks cache enables efficient authentication and authorization at scale by proactively refreshing cached objects.
- [Monitoring & Analytics](https://docs.cybus.io/2-4-0/broker/cybusmq/configuration/monitoring-and-analytics.md): Monitoring and analytics capabilities of CybusMQ.
- [Operating CybusMQ](https://docs.cybus.io/2-4-0/broker/cybusmq/operations.md): Operational and maintenance tasks for CybusMQ.
- [MQTT Broker Storage Volumes in Kubernetes](https://docs.cybus.io/2-4-0/broker/cybusmq/operations/mqtt-broker-storage-volumes-in-kubernetes.md): Configure initial storage sizes for new deployments and resize existing broker volumes in Kubernetes environments.
- [Scaling the Broker Cluster](https://docs.cybus.io/2-4-0/broker/cybusmq/operations/scaling-the-broker-cluster.md): Scale the MQTT broker cluster up, down, or to zero.
- [Deleting Broker Data Volumes](https://docs.cybus.io/2-4-0/broker/cybusmq/operations/deleting-broker-data-volumes.md): Delete broker data volumes to remove persistent MQTT data.
- [Environment Variables (CybusMQ)](https://docs.cybus.io/2-4-0/broker/cybusmq/environment-variables.md): Environment variables for configuring CybusMQ.


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