When hardening a server's security, what should be the priority regarding active services?

The priority when hardening a server's security is to keep only essential services active. This approach minimizes attack surfaces, as each running service can potentially introduce vulnerabilities. By deactivating unnecessary services, you significantly reduce the risk of exploitation, as attackers often target services that are not secured properly or that have known vulnerabilities.

Keeping only essential services active aligns with the principle of least privilege, which dictates that systems should operate at the minimum level necessary for function. It simplifies security management, making it easier to apply and monitor security measures effectively. Moreover, this strategy ensures that resources are allocated efficiently and that there are fewer opportunities for malicious activities.

The other options do not prioritize security effectively. Running all services for redundancy can create multiple entry points for attackers. Monitoring services from the outside does not eliminate vulnerabilities; it only allows for observation without addressing potential threats. Lastly, while running the latest updates is essential for security, it does not negate the need to minimize active services; updates alone do not prevent exploitation if unnecessary services are still running.