How can you make an EC2 instance resilient to failure?

Using an Auto Scaling group across multiple Availability Zones is an effective strategy to make an EC2 instance resilient to failure. This approach allows for the automatic scaling of instances based on demand and ensures high availability by distributing instances across different Availability Zones within a region. If one Availability Zone experiences an outage, the Auto Scaling group can launch new instances in another Availability Zone to maintain application availability. This capability provides not only redundancy but also the flexibility to handle varying loads efficiently.

Other options, while related to Amazon services, do not provide the same level of resilience. For example, Amazon RDS is a managed database service and, while it can be part of an application's architecture, it does not enhance the resilience of EC2 instances directly. Deploying a single instance does not provide redundancy; if that instance fails, your application becomes unavailable. Finally, using a static IP address is primarily a networking configuration and does not inherently include features to handle instance failures or ensure continuity of service. Thus, leveraging an Auto Scaling group is the most effective method for ensuring resiliency against instance failures.