Final answer:
An authenticated scan provides the most accurate and detailed information about the security state of a server.
Step-by-step explanation:
The most accurate and detailed information about the security state of a server can be obtained through an authenticated scan. An authenticated scan requires proper login credentials and allows the scanning tool to access privileged information and perform a thorough analysis of the server's security.
In contrast, an unauthenticated scan only provides limited information as it does not require logins and can only identify vulnerabilities that can be detected without authentication. A port scan, which checks for open ports on a server, offers a basic view of the server's accessibility from the network but does not reveal detailed security information. Lastly, a half-open scan attempts to connect to a target, but then disconnects before the connection is established, providing limited detail about open ports.
Overall, an authenticated scan is the most reliable and in-depth way to assess the security state of a server.