> For the complete documentation index, see [llms.txt](https://stephen-tsoi.gitbook.io/stephen-tsoi-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://stephen-tsoi.gitbook.io/stephen-tsoi-docs/messaging-troubleshooting/a-missing-event-among-billions-how-we-found-it-on-an-event-mesh/day-3-13-event-broker-failover-or-network-disconnect.md). # Day 3/13 Event Broker Failover or Network Disconnect Even if the sending application has done everything right according to the preview post discussion (), there is still a very small chance of events missing due to other factors such as **event broker high availability (HA)** or **disaster recovery (DR) failover** if the correct broker settings are NOT being applied. Network connectivity also impacts event message delivery across the event mesh through dynamic message routing (DMR) or VPN Bridge. Therefore, it is crucial to carefully configure the event broker, and perform failover and DR testing. For instance, if the is subscribing application is using direct topic subscriptions (non-persistent), all event messages in-flight to that subscriber will be lost during event broker HA or DR failover. The table below provides a summary of various scenarios for the direct and persistent event message.
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