What system architecture can be utilized to limit dial-up connections?

The correct approach to limiting dial-up connections involves the use of whitelists for specific phone numbers. Implementing a whitelist means that only pre-approved phone numbers can establish a dial-up connection to a network. This significantly enhances security by ensuring that connections can only be made from trusted sources, reducing the risk of unauthorized access.

Whitelisting effectively restricts dial-up access to known and verified users or systems, aiding in the prevention of potential threats that unsecured dial-up connections can introduce. By employing this method, organizations can maintain tighter control over who is allowed to connect, which is especially critical in environments that manage sensitive information or essential infrastructure.

Other options, such as shared access numbers and anonymous connection setups, do not contribute effectively to controlling or limiting access in this context. Shared access could inadvertently allow unauthorized users to gain entry, and anonymous setups do not provide traceability or accountability. Additionally, the idea of not needing controls is contrary to the principles of good security practices, especially in managing access to critical infrastructure. Implementing robust access controls like whitelists is essential for maintaining the integrity and confidentiality of systems.