The most likely reason the computer is unable to boot into the imaging system via the network is that the PXE boot option has not been enabled. PXE (Preboot Execution Environment) is an environment that allows computers to boot up over the network, instead of from a local disk. In order for this to work, the PXE boot option must be enabled in the computer's BIOS settings. As stated in the CompTIA A+ Core 2 exam objectives, technicians should know how to enable PXE in BIOS to enable network booting on a computer.

The workstations and the authentication server have a system clock difference. If a Group Policy setting is applied that forces the workstations to use a specific SNTP server, but the system clock on the workstations and the authentication server are out of sync, then this can cause authentication issues and users will be unable to log in. In this case, the most likely cause of the issue is a difference in system clocks and the technician should ensure that the clocks on the workstations and the authentication server are in sync.

A workgroup is a network configuration that allows computers to communicate and share resources with each other without requiring a centralized server or domain controller. A workgroup is suitable for small office environments where there are only a few computers and users who need simple file and printer sharing. A workgroup does not have centralized management or security policies, which may be desirable for larger or more complex networks. Print server, virtualization, and domain access are not network configurations that are most likely used in a small office environment.

A virtual private network (VPN) is a technology that creates a secure and encrypted connection over a public network, such as the internet. A VPN allows remote employees to access the corporate intranet as if they were physically connected to the local network3. Password-protected Wi-Fi is a security measure for wireless networks that does not provide access to the corporate intranet. Port forwarding is a technique that allows external devices to access services on a private network through a router, but does not provide access to the corporate intranet. A perimeter network is a network segment that lies between an internal network and an external network, such as the internet, and provides an additional layer of security, but does not provide access to the corporate intranet.

Private-browsing mode is the best option to mitigate the risk of customer data being accidentally saved to the kiosk. Private-browsing mode prevents the browser from storing cookies, history, passwords, and other data that could reveal the customer's identity or preferences. Manually clearing browsing data is not a reliable option, as it depends on the customer's awareness and willingness to do so. Browser data synchronization and password manager are features that could actually increase the risk of customer data being exposed, as they could sync or autofill sensitive information across devices or accounts. Reference:
Official CompTIA learning resources CompTIA A+ Core 1 and Core 2, page 12 Certification Study Guides and Books | CompTIA IT Certifications, CompTIA A+ Core 1 220-1101 Certification Study Guide, page 234