Availability zones are logical data centers within a cloud region that are isolated and independent from each other. Availability zones have their own power, cooling, and networking infrastructure, and are connected by low-latency networks. Availability zones help to ensure high availability and fault tolerance for cloud applications by allowing customers to deploy their resources across multiple zones within a region. If one availability zone experiences an outage or maintenance, the other zones can continue to operate and serve the application12
To ensure the CSP does not bring both servers down for maintenance at the same time, the cloud administrator must configure the application to use availability zones. The administrator can deploy the two database servers in different availability zones within the same region, and enable replication and synchronization between them. This way, the application can access either server in case one of them is unavailable due to maintenance or failure. The administrator can also use load balancers and health checks to distribute the traffic and monitor the status of the servers across the availability zones34
Backups are not the best option to ensure the CSP does not bring both servers down for maintenance at the same time, because backups are copies of data that are stored in another location for recovery purposes. Backups can help to restore the data in case of data loss or corruption, but they do not provide high availability or fault tolerance for the application. Backups are usually performed periodically or on-demand, rather than continuously. Backups also require additional storage space and bandwidth, and may incur additional costs.
Autoscaling is not the best option to ensure the CSP does not bring both servers down for maintenance at the same time, because autoscaling is a feature that allows customers to scale their cloud resources up or down automatically, based on predefined conditions such as traffic or utilization levels. Autoscaling can help to optimize the performance and costs of the application, but it does not guarantee high availability or fault tolerance for the application. Autoscaling maynot be able to scale the resources fast enough to handle sudden spikes or drops in demand, and it may also introduce additional complexity and overhead for managing the resources.
Replication is not the best option to ensure the CSP does not bring both servers down for maintenance at the same time, because replication is a process of copying and synchronizing data across multiple locations or devices. Replication can help to improve the availability and consistency of the data, but it does not prevent the CSP from bringing both servers down for maintenance at the same time. Replication also depends on the availability and connectivity of the locations or devices where the data is replicated, and it may also increase the network traffic and storage requirements.
[References: 1: https://learn.microsoft.com/en-us/azure/reliability/availability-zones-overview 2: https://www.comptia.org/training/books/cloud-essentials-clo-002-study-guide, page 42 3: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.RegionsAndAvailabilityZones.html 4: https://docs.aws.amazon.com/elasticloadbalancing/latest/userguide/how-elastic-load-balancing-works.html : https://www.comptia.org/training/books/cloud-essentials-clo-002-study-guide, page 44 : https://www.comptia.org/training/books/cloud-essentials-clo-002-study-guide, page 46 : https://www.comptia.org/training/books/cloud-essentials-clo-002-study-guide, page 48, , , ]
