Which action is NOT recommended for securing devices in the datacenter?

Permitting multiple default passwords is not recommended for securing devices in the datacenter because it could significantly increase the risk of unauthorized access. Default passwords are often well-known or easily accessible, making devices vulnerable to exploitation. By allowing multiple default passwords, the security posture of the datacenter is compromised, as it becomes easier for potential attackers to utilize these common credentials to gain access to sensitive systems.

In contrast, actions such as removing all guest accounts, regularly patching and updating systems, and closing unused system ports are all critical practices in maintaining a secure datacenter environment. Removing guest accounts reduces the number of potential entry points for attackers. Regularly patching and updating systems addresses vulnerabilities and closes security gaps that could be exploited. Closing unused system ports minimizes the attack surface by reducing opportunities for unauthorized access. Therefore, avoiding the use of multiple default passwords is essential for effective security management in a datacenter.