To effectively prevent downgrade attacks on Apache web servers, what should Casey do?

Preventing downgrade attacks on Apache web servers primarily involves addressing vulnerabilities that arise when an attacker manipulates a connection to force older, less secure protocols to be used. This is often accomplished through mechanisms like the TLS protocol, which is designed to provide strong security for web communications.

By preventing TLS fallback, Casey would ensure that the server does not allow clients to revert to older versions of TLS or SSL, which may have well-known vulnerabilities (like POODLE or BEAST). This means configuring the server to only support the most current and secure versions of TLS, thereby reducing the attack surface significantly. By enforcing this policy, Casey can protect users from being coerced into using weaker encryption that could be exploited by an attacker.

The other options do not address the specific issue of downgrade attacks effectively. For instance, implementing stronger passwords relates to user authentication, not the protocol negotiations during secure connections. Avoiding SSL altogether might seem like it would prevent downgrade attacks, but it does not address the actual vulnerabilities inherent in using older protocols for negotiation. Finally, while enabling HTTP/2 can improve performance and security features, it does not directly relate to preventing downgrade attacks if the underlying encryption protocols are not adequately enforced.