The most appropriate native protocol to use for connecting a Linux server to a share on a NAS is NFS. NFS (Network File System) is a protocol that allows file sharing and remote access over a network. NFS is designed for Unix-like operating systems, such as Linux, and supports features such as symbolic links, hard links, file locking, and file permissions. NFS uses mount points to attach remote file systems to local file systems, making them appear as if they are part of the local file system. NFS can provide fast and reliable access to files stored on a NAS (Network Attached Storage), which is a device that provides centralized storage for network devices.

The cache is a temporary storage area that holds frequently accessed data or instructions for faster retrieval. The cache can improve the read times for accessing files by reducing the need to access the hard drive, which is slower than the cache memory1. Therefore, the first step the technician should take is to check if the cache is turned on for the new file server. If the cache is turned off, the technician should enable it and see if the read times improve. The other options are incorrect because they are not the first steps to take.
Adding more memory, installing faster hard drives, or enabling link aggregation are possible ways to improve the performance of the file server, but they are more costly and time-consuming than checking the cache.
Moreover, they may not address the root cause of the problem if the cache is turned off.

Explanation
A SD card is a type of flash memory card that can be used to store data and run applications. A SD card can be used to install a Type 1 hypervisor on a server, as it provides fast boot time, low power consumption, and high reliability. A Type 1 hypervisor runs directly on the underlying computer's physical hardware, interacting directly with its CPU, memory, and physical storage. For this reason, Type 1 hypervisors are also referred to as bare-metal hypervisors. A Type 1 hypervisor takes the place of a host operating system and VM resources are scheduled directly to the hardware by the hypervisor123. A NAS drive (B) is a type of network-attached storage (NAS) device that provides shared access to files and data over a network. A NAS drive cannot be used to install a Type 1 hypervisor on a server, as it requires a network connection and a host operating system to function. A SATA drive is a type of hard disk drive (HDD) or solid state drive (SSD) that uses the Serial ATA (SATA) interface to connect to a computer. A SATA drive can be used to install a Type 1 hypervisor on a server, but it may have some disadvantages compared to a SD card, such as slower boot time, higher power consumption, and lower reliability. A SAS drive (D) is a type of hard disk drive (HDD) or solid state drive (SSD) that uses the Serial Attached SCSI (SAS) interface to connect to a computer. A SAS drive can also be used to install a Type 1 hypervisor on a server, but it may have similar disadvantages as a SATA drive, and it may also be more expensive and less compatible than a SD card. References:
https://phoenixnap.com/kb/what-is-hypervisor-type-1-2 https://www.ibm.com/topics/hypervisors 3
https://www.redhat.com/en/topics/virtualization/what-is-a-hypervisor

Changing the boot order on the server and restricting console access would prevent unauthorized access attempts via USB devices at startup, as the server would not boot from any external media and only authorized users could access the console. Setting a BIOS/UEFI password on the server would also help, but it could be bypassed by resetting the CMOS battery or using a backdoor password. Configuring the host OS to deny login attempts via USB would not prevent booting from a malicious USB device that could compromise the system before the OS loads. Disabling all the USB ports on the server would limit functionality, as some peripherals or devices may need to use them. Reference:
https://www.pcmag.com/how-to/dont-plug-it-in-how-to-prevent-a-usb-attack
https://www.techopedia.com/definition/10362/boot-order
https://www.techopedia.com/definition/10361/console-access
https://www.techopedia.com/definition/102/bios-password
https://www.techopedia.com/definition/10363/cmos-battery

The server is infected with a virus and SELinux is enabled on the server are most likely causing the issue of unauthorized services running on the server. A virus is a type of malicious software that infects a system and performs unwanted or harmful actions, such as creating, modifying, deleting, or executing files. A virus can also create backdoors or open ports on a system to allow remote access or communication with external sites. SELinux (Security-Enhanced Linux) is a security module for Linux systems that enforces mandatory access control policies on processes and files. SELinux can prevent unauthorized services from running on a server by restricting their access to resources based on their security context. However, SELinux can also cause problems if it is not configured properly or if it conflicts with other security tools.