Which can be used to ensure that your Autonomous Database is accessible only from a given set of IPs?

Autonomous Database includes a built-in security feature called an Access Control List (ACL). An ACL allows you to restrict network access to the database by specifying a list of allowed IP addresses, CIDR blocks, or Virtual Cloud Networks (VCNs). When an ACL is enabled, the Autonomous Database will only accept connections originating from the entries defined in the list, effectively ensuring that the database is accessible only from a given set of IPs. This is the primary, service-native method for IP-based access control.

A. Security List: Security Lists are a Virtual Cloud Network (VCN) feature that acts as a virtual firewall for subnets, not a feature specific to the Autonomous Database service itself.
B. IP Vault: This is not a recognized feature or term within Oracle Cloud Infrastructure or Autonomous Database for managing network access.
D. IPSec List: IPSec is a protocol for securing network communications through encryption and authentication, not a feature for defining a list of allowed source IP addresses for database connections.

1. Oracle Cloud Infrastructure Documentation, "Configure Access Control Lists for an Autonomous Database": "You can configure an access control list (ACL) for your Autonomous Database instance to restrict access to the database to a specified set of IP addresses or VCNs. When you enable an ACL, your Autonomous Database instance only accepts connections from IP addresses on the access control list." (Service: Autonomous Database, Document ID: E94116-27, Section: "Configure Access Control Lists for an Autonomous Database")

2. Oracle Cloud Infrastructure Documentation, "Security Features of Autonomous Database": Under the "Network Security" section, it details the use of Access Control Lists (ACLs). "By default, Autonomous Database is accessible from all secure endpoints, but you can restrict access by enabling an access control list (ACL) and adding IP addresses or VCNs to the list." (Service: Autonomous Database, Document ID: F32168-12, Chapter: "Security Features of Autonomous Database", Section: "Network Security")