What it means
Server clustering and failover coordinate nodes, health checks, quorum, replication, service ownership, and recovery behavior so workloads can continue after selected failures.
Why it matters
High availability depends on correct failure detection and sufficient remaining capacity; duplicated servers alone do not guarantee a safe transition.
Practical focus
- Define the failures, dependencies, and recovery objectives the cluster must handle and the security outcome it must support
- Apply appropriate quorum, independent failure domains, health logic, synchronized state, and tested failover through documented, reviewable configuration
- Verify node health, split-brain indicators, replication lag, failover duration, and capacity after failure after changes and on a scheduled basis
- Plan for a shared dependency or incorrect health check causing simultaneous or false failover, including rollback, ownership, and escalation
Common mistakes
- Enabling a feature without defining what it should protect
- Relying on defaults or one-time validation
- Granting broad exceptions that erase the control boundary
- Treating a shared dependency or incorrect health check causing simultaneous or false failover as an operational surprise instead of a test case
Certification relevance
This subject appears in or supports the following certification bodies of knowledge: