A server has multiple fans inside the chassis to cool down the components and prevent overheating. If one of the fans fails, it can cause the server to reboot and crash due to thermal issues. A failed fan can also make loud noises due to friction or vibration. The administrator should check the fans and clean them from dust and debris, or replace them if they are damaged12.
References = 1: It's Too Loud! 3 Solutions to Remedy Server Noise - Computerware Blog | DC Metro | Computerware Blog(https://www.cwit.com/blog/it-s-too-loud-3-solutions-to-remedy-server-noise) 2: What factors affect the noise level of a server? - Server Fault(https://serverfault.com/questions/430550/what-factors-affect-the-noise-level-of-a-server)

Few people are expected to use the database at the same time and users don't need to customize the design of the database.
Reference:
The server role that the administrator will most likely need to install for a server that will hold large amounts of information and will need to be accessed by multiple users at the same time is database. A database is a collection of structured data that can be stored, queried, manipulated, and analyzed using various methods and tools. A database server is a server that hosts one or more databases and provides access to them over a network. A database server can handle large amounts of information and support concurrent requests from multiple users or applications.

The # symbol is used to write a text description per line within a PowerShell script. A text description is also known as a comment, which is a line of code that is ignored by the PowerShell interpreter and serves as documentation or explanation for human readers. The # symbol indicates that everything following it on the same line is a comment and not part of the script commands or expressions. For example:
This is a comment in PowerShell
Write-Host "Hello World" # This command prints Hello World to the console

Explanation
Per concurrent user licensing is a model that allows a fixed number of users to access the software at any one point in time. This model is best for the company that wants to deploy software to all users, but very few of them will be using the software at any one point in time. This way, the company can save money by paying only for the number of simultaneous users, rather than for every user who has access to the software. Per site licensing is a model that allows unlimited users within a specific location to use the software. Per core licensing is a model that charges based on the number of processor cores on the server where the software is installed. Per instance licensing is a model that charges based on the number of copies of the software running on different servers or virtual machines. References:
https://www.pcmag.com/encyclopedia/term/concurrent-use-license
https://www.techopedia.com/definition/1440/software-licensing