Which of the following is NOT an optional piece of LDAP/Active Directory server information?

The answer indicating that password complexity requirements are not an optional piece of LDAP/Active Directory server information is correct because password complexity is a fundamental security setting within Active Directory that governs how passwords are created and modified. This requirement ensures that passwords meet certain standards for strength, which helps to secure user accounts from unauthorized access.

In the context of configuring a system that connects to LDAP or Active Directory, it is crucial for the application or service to adhere to these password policies to ensure compliance with the directory's security posture. If password complexity requirements were considered optional, it could lead to weaker password protection, compromising the security of user accounts and the organization as a whole.

Other elements like the IP address of the LDAP server, credentials with administrative read rights, and user schema settings, while important for the successful integration and operation of systems interacting with LDAP/Active Directory, can be configured based on the specific needs or permissions of the organization. These items may not always be necessary for all configurations, depending on the context of use, making them optional in that sense. However, adhering to password complexity requirements is a non-negotiable aspect of secure directory service implementation.