This is the best action to perform before applying patches to one of the hosts in a high availability cluster. A high availability cluster is a group of hosts that act like a single system and provide continuous uptime. A high availability cluster is often used for load balancing, backup, and failover purposes. Failover is a process of transferring workloads from one host to another in case of a failure or maintenance. By failing over all VMs (Virtual Machines) from the host that needs to be patched to another host in the cluster, the technician can ensure that there is no downtime or data loss during the patching process. Disabling the heartbeat network is not a good action to perform, as this would disrupt the communication and synchronization between the hosts in the cluster. Fallback cluster services is not a valid term, but it may refer to restoring cluster services after a failover, which is not relevant before applying patches. Setting the cluster to active-active is not a good action to perform, as this would increase the load on both hosts and reduce redundancy. References:
https://www.howtogeek.com/190014/virtualization-basics-understanding-techniques-and-fundamentals/
https://www.howtogeek.com/428483/what-is-end-to-end-encryption-and-why-does-it-matter/

The best immediate actions to prevent unauthorized server access are to stop all unneeded services and block the ports on the firewall. Stopping unneeded services reduces the attack surface of the server by eliminating potential entry points for attackers. For example, if the server is not functioning as a web server, there is no need to run a web service on port 80. Blocking ports on the firewall prevents unauthorized network traffic from reaching the server. For example, if port 80 is not needed for any legitimate purpose, it can be blocked on the firewall to deny any connection attempts on that port.

Reflective glass is an architectural reinforcement that attempts to conceal the interior of an organization by reflecting light and preventing outsiders from seeing inside. Reflective glass can also reduce heat and glare, and enhance the aesthetic appearance of a building. Reflective glass is often used in high-security facilities, such as data centers, government buildings, or corporate headquarters12
1: Server Architecture for CompTIA Server+ (SK0-004) | Pluralsight 2: Introducing the CompTIA Infrastructure Career Pathway

A blade server is a type of server that is installed in a chassis or an enclosure that provides power, cooling, networking, and management features. The blade server does not have any cables attached to it, as it connects to the chassis through a midplane or a backplane. A blade server can save space, energy, and cost compared to other types of servers. Verified References: [Blade server], [Chassis]

A tower server is a type of server architecture that is best suited to minimize cost when deploying a single server to monitor and record the security cameras at a remote site. A tower server is a standalone server that has a similar form factor and design as a desktop computer. It does not require any special mounting equipment or rack space and can be placed on or under a desk or table. A tower server is suitable for small businesses or remote offices that need only one or few servers for basic tasks such as file sharing, print serving, or security monitoring. A tower server is usually cheaper and easier to maintain than other types of servers, but it may have lower performance, scalability, and redundancy features. A virtual server is a type of server architecture that involves creating and running one or more virtual machines on a physical host using a hypervisor such as Hyper-V or VMware. A virtual server can reduce hardware costs and improve flexibility and efficiency, but it requires additional software licenses and management tools. A blade server is a type of server architecture that involves inserting multiple thin servers called blades into a chassis that provides power, cooling, network, and management features. A blade server can improve performance, density, and scalability, but it requires more initial investment and specialized equipment. A rack mount server is a type of server architecture that involves mounting one or more servers into standardized frames called racks that provide power, cooling, network, and security features