This feature requires Consul Enterprise with the Global Visibility, Routing, and Scale module.
Consul Enterprise redundancy zones provide both scaling and resiliency benefits by enabling the deployment of non-voting servers alongside voting servers on a per availability zone basis.
When using redundancy zones, if an operator chooses to deploy Consul across 3 availability zones, they could have 2 (or more) servers (1 voting/1 non-voting) in each zone. In the event that a voting member in an availability zone fails, the redundancy zone configuration would automatically promote the non-voting member to a voting member. In the event that an entire availability zone was lost, a non-voting member in one of the existing availability zones would promote to a voting member, keeping server quorum. This capability functions as a "hot standby" for server nodes while also providing (and expanding) the capabilities of enhanced read scalability by also including recovery capabilities.