Helping Hand Questions for 1z0-1085-23

The primary use case for using Web Application Firewall (WAF) in OCI is to filter malicious web traffic and protect internet-facing and internal applications from attacks. WAF is a cloud-based, PCI-compliant, global web application firewall service that monitors and controls access to web applications based on predefined rules and threat intelligence. WAF can block common web application attacks such as cross-site scripting (XSS), SQL injection, remote file inclusion, etc., as well as bot traffic, geographic restrictions, rate limiting, etc. WAF can protect any internet-facing endpoint or internal application by attaching WAF policies to enforcement points such as load balancers or web application domain names10

For highest level of resilience you can deploy the application between regions and distribute on availability domain and fault domains.

Changing the Shape of an Instance (Horizontal Scaling)

You can change the shape of a virtual machine (VM) instance without having to rebuild your instances or redeploy your applications. This lets you scale up your Compute resources for increased performance, or scale down to reduce cost.

Autoscaling (vertical scaling)

Autoscaling lets you automatically adjust the number of Compute instances in an instance pool based on performance metrics such as CPU utilization. This helps you provide consistent performance for your end users during periods of high demand, and helps you reduce your costs during periods of low demand.

As load increases, instances are automatically provisioned: the instance pool scales out. As load decreases, instances are automatically removed: the instance pool scales in.

https://docs.cloud.oracle.com/en-us/iaas/Content/Compute/Tasks/resizinginstances.htm