> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vortexiq.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Node Down (DN) or Gossip Flapping, Apache Cassandra KPI card, Vortex IQ Nerve Centre

> Cassandra-distinctive - a DN node reduces replica availability; sustained = consistency-level failures imminent. Page on-call.

**[Nerve Centre KPIs](/nerve-centre/kpi-cards/cassandra) · [Audit Profile](/nerve-centre/kpi-cards/cassandra/audit) · [Sentiment Settings](/nerve-centre/kpi-cards/cassandra/sentiment)**

## At a glance

* **Category:** Nerve Centre
* **Type:** Key Metrics
* **Chart:** alert\_list
* **Format:** number
* **Time window:** RT
* **Alert trigger:** any endpoint in DN state OR gossip marks peer DOWN

## Calculation

Cassandra-distinctive - a DN node reduces replica availability; sustained = consistency-level failures imminent. Page on-call.

## Known limitations

*Known limitations, FAQs, or reconciliation notes specific to this card. Replace this block when authored.*