What is redundancy?
In terms of hosting, redundancy means that if an infrastructure component fails, another backup or redundant one takes over to continue operations with minimum or no downtime or service disruption.
What are the available redundancy levels?
None: there are no redundancy measures, any critical failure will bring the service down and operations will be disrupted until a manual intervention is conducted.
Server: if a server in the same cluster fails, the instance will be automatically switched to another server without any downtime, and the service will continue normal operations without any disruption.
Internet: if an internet provider is down or becomes unavailable, the traffic will be automatically routed through another provider without any downtime, and the service will continue normal operations without any disruption.
Data Center: if a data center in a specific region fails, the instance will be automatically switched to another data center in the same or another region without any downtime, and the service will continue normal operations without any disruption.
The highest level of redundancy is Data Center, as it includes both Server and Internet level redundancies in a global scale.
