The technician should boot from the media to install the firmware on the server. Firmware is a type of software that controls the low-level functions of hardware devices, such as BIOS (Basic Input/Output System), RAID controllers, network cards, etc. Firmware updates are often provided by hardware manufacturers to fix bugs, improve performance, or add new features to their devices. To install firmware updates on a server, the technician needs to boot from a media device (such as a CD-ROM, DVD-ROM, USB flash drive, etc.) that contains the firmware files and installation program. The technician cannot install firmware updates from within the operating system because firmware updates often require restarting or resetting the hardware devices.

The type of data replication that is required for a hot-site disaster recovery model is constant. A hot site is a type of disaster recovery site that has fully operational IT infrastructure and equipment that can take over the primary site's functions immediately in case of a disaster or disruption. A hot site requires constant data replication between the primary site and the hot site to ensure that the data is up-to-date and consistent.
Constant data replication means that any changes made to the data at the primary site are immediately copied to the hot site without any delay or lag.

Port 21 is used for FTP (File Transfer Protocol), which is a protocol that transfers files between servers and clients in cleartext, meaning that anyone can intercept and read the data. To stop this communication, port 21 should be closed on the web server and replaced with a secure protocol, such as SFTP (Secure File Transfer Protocol) or FTPS (File Transfer Protocol Secure), which use encryption to protect the data. Verified References: [FTP vs SFTP vs FTPS]

Round robin is an example of load balancing. Load balancing is the method of distributing network traffic equally across a pool of resources that support an application. Load balancing improves application availability, scalability, security, and performance by preventing any single resource from being overloaded or unavailable. Round robin is a simple load balancing algorithm that assigns each incoming request to the next available resource in a circular order. For example, if there are three servers (A, B, C) in a load balancer pool, round robin will send the first request to server A, the second request to server B, the third request to server C, the fourth request to server A again, and so on.

Log rotation is a process that periodically renames, compresses, and deletes old log files to free up disk space and keep log files manageable. Log rotation can be configured using tools such as logrotate or cron on Linux systems, or using Windows Task Scheduler or PowerShell scripts on Windows systems. Log rotation can also help with log analysis and troubleshooting by making it easier to find relevant information in smaller and more recent log files. References:
https://www.mezmo.com/learn-log-management/what-is-log-rotation-how-does-it-work
https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/logman