Oracle Functions is a fully managed, multi-tenant, highly scalable, on-demand, Functions-as-a-Service platform. It is built on enterprise-grade Oracle Cloud Infrastructure and powered by the Fn Project open source engine. Use Oracle Functions (sometimes abbreviated to just Functions) when you want to focus on writing code to meet business needs.
The serverless and elastic architecture of Oracle Functions means there's no infrastructure administration or software administration for you to perform. You don't provision or maintain compute instances, and operating system software patches and upgrades are applied automatically. Oracle Functions simply ensures your app is highly-available, scalable, secure, and monitored. With Oracle Functions, you can write code in Java, Python, Node, Go, and Ruby (and for advanced use cases, bring your own Dockerfile, and Graal VM). You can then deploy your code, call it directly or trigger it in response to events, and get billed only for the resources consumed during the execution.
You can create automation based on state changes for your Oracle Cloud Infrastructure resources by using event types, rules, and actions. When the function is executing inside the container, the function can read from and write to other resources and services running in the same subnet (for example, Database as a Service). The function can also read from and write to other shared resources (for example, Object Storage), and other Oracle Cloud Services.

Autonomous Database is an Oracle Managed and Secure environment.
A physical database can't simply be migrated to autonomous because:
- Database must be converted to PDB, upgraded to 19c, and encrypted
- Any changes to Oracle shipped privileges, stored procedures or views must be removed
- All legacy structures and unsupported features must be removed (e.g. legacy LOBs) GoldenGate replication can be used to keep database online during migration

Explanation
Oracle and Microsoft have created a cross-cloud connection between Oracle Cloud Infrastructure and Microsoft Azure in certain regions. This connection lets you set up cross-cloud workloads without the traffic between the clouds going over the internet.
you can connect your VNet and VCN so that traffic that uses private IP addresses goes over the crosscloud connection.
For example, the following diagram shows a VNet that is connected to a VCN. Resources in the VNet are running a .NET application that access an Oracle database that runs on Database service resources in the VCN.
The traffic between the application and database uses a logical circuit that runs on the cross-cloud connection between Azure and Oracle Cloud Infrastructure.
The two virtual networks must belong to the same company and not have overlapping CIDRs.
The connection requires you to create an Azure ExpressRoute circuit and an Oracle Cloud Infrastructure FastConnect virtual circuit.

WAF can protect any internet facing endpoint, providing consistent rule enforcement across a customer's applications.
WAF provides you with the ability to create and manage rules for internet threats including Cross-Site Scripting (XSS), SQL Injection and other OWASP-defined vulnerabilities. Unwanted bots can be mitigated while tactically allowed desirable bots to enter. Access rules can limit based on geography or the signature of the request.
As a WAF administrator you can define explicit actions for requests that meet various conditions. Conditions use various operations and regular expressions. A rule action can be set to log and allow, detect, or block requests

An internet gateway is an optional virtual router you can add to your VCN to enable direct connectivity to the internet. Resources that need to use the gateway for internet access must be in a public subnet and have public IP addresses. Each public subnet that needs to use the internet gateway must have a route table rule that specifies the gateway as the target. For traffic to flow between a subnet and an internet gateway, you must create a route rule accordingly in the subnet's route table (for example, destination CIDR = 0.0.0.0/0 and target = internet gateway).
Dynamic Routing Gateway (DRG) is A virtual edge router attached to your VCN. Necessary for private peering. The DRG is a single point of entry for private traffic coming in to your VCN,After creating the DRG, you must attach it to your VCN and add a route for the DRG in the VCN's route table to enable traffic flow.