A faulty PSU needs replacement, and the management team wants a solution to prevent future downtime.
Solution: Implement redundancy (Option D):
Redundant power supplies ensure that if one fails, the other takes over seamlessly.
Separate circuits, load balancing, and server monitoring are important but do not directly prevent PSU failures.

Archive is a method of storing historical data that is not frequently accessed or modified. Archive can reduce the amount of data that needs to be backed up and save bandwidth and storage space. Differential is a method of backing up only the data that has changed since the last full backup. Differential can also save bandwidth and storage space, as well as speed up the backup process.
References:
CompTIA Server+ Certification Exam Objectives1, page 12
Server Management: Server Hardware Installation and Management2, Module 2, Lesson 5

Explanation
The administrator should use a subnet mask of 255.255.255.0 for this setup. A subnet mask is a binary number that defines how many bits of an IP address are used for the network portion and how many bits are used for the host portion. The network portion identifies the specific network that the IP address belongs to, while the host portion identifies the specific device within that network. The subnet mask is usually written in dotted decimal notation, where each octet represents eight bits of the binary number. A 1 in the binary number means that the corresponding bit in the IP address is part of the network portion, while a 0 means that it is part of the host portion. For example, a subnet mask of 255.255.255.0 means that the first 24 bits (three octets) of the IP address are used for the network portion and the last 8 bits (one octet) are used for the host portion. This subnet mask allows up to 254 hosts per network (2^8 - 2). In this case, the IP address of 10.20.10.15 and the default gateway of 10.20.10.254 belong to the same network of 10.20.10.0/24 (where /24 indicates the number of bits used for the network portion), which can be defined by using a subnet mask of 255.255.255.0.

Updating the firmware on the NIC is the most likely solution to fix the issue of a new 40GB NIC not being detected within the Windows server OS. Firmware is a software program that controls the functionality of a hardware device, such as a NIC (network interface card). A NIC is a device that enables network communication for a server by providing an interface between the server and the network cable or wireless connection. Updating the firmware on the NIC can improve its performance, compatibility, and stability with the server OS and network protocols. References: CompTIA Server+ Certification Exam Objectives, Domain
4.0: Networking, Objective 4.1: Given a scenario, configure network settings for servers.

The first action that the administrator should take before swapping out the GPU card inside a server is to shut down the server. This is to ensure that the server is not running any processes that might be using the GPU card, and to prevent any damage to the hardware or data loss due to sudden power loss. Shutting down the server also reduces the risk of electrostatic discharge (ESD) that might harm the components. Reference: https://pcgearhead.com/installing-a-new-gpu/