CompTIA Updated XK0-005 Exam Questions and Answers by amaia

The command that would ensure the server is set to runlevel 5 is systemct1 isolate graphical.target. This command will change the current target (or runlevel) of systemd to graphical.target, which is equivalent to runlevel 5 in SysV init systems. Graphical.target means that the system will start with a graphical user interface (GUI) and all services required for it.

The other options are not correct commands for setting the server to runlevel 5. The systemct1 isolate multi-user.target command will change the current target to multi-user.target, which is equivalent to runlevel 3 in SysV init systems. Multi-user.target means that the system will start with multiple user logins and networking, but without a GUI. The systemct1 isolate network.target command will change the current target to network.target, which is not a real runlevel but a synchronization point for network-related services. Network.target means that network functionality should be available, but does not specify whether it should be started before or after it. The systemct1 isolate basic.target command will change the current target to basic.target, which is also not a real runlevel but a synchronization point for basic system services. Basic.target means that all essential services should be started, but does not specify whether it should be started before or after it. References: systemd System and Service Manager; systemd.special(7) - Linux manual page

The command that would allow a user to choose a stronger password and set it on the existing SSH key file is ssh-keygen -p -f . This command uses the ssh-keygen tool, which is used to generate, manage, and convert authentication keys for SSH. The -p option stands for passphrase, and it allows the user to change or remove the passphrase of an existing private key file. The -f option specifies the filename of the key file. The command will prompt the user for the old passphrase, and then for the new passphrase twice.

The other options are not correct commands for changing the password of an SSH key file. The passwd command is used to change the password of a user account on a Linux system, not an SSH key file. The ssh command is used to log in to a remote system using SSH, not to change the password of an SSH key file. The pwgen command is used to generate random passwords, not to change the password of an SSH key file.

References: ssh-keygen(1) - Linux manual page; How To: Change Passphrase for SSH Private Key - Unix Tutorial

The command docker rm $(docker ps -aq) will allow the administrator to clean up the containers in an exited state. The docker command is a tool for managing Docker containers on Linux systems. Docker containers are isolated and lightweight environments that can run applications and services without affecting the host system. Docker uses images to create containers, which are files that contain the code, libraries, dependencies, and configuration of the applications and services. The rm option removes one or more containers. The $(docker ps -aq) is a command substitution that executes the command inside the parentheses and replaces it with the output. The docker ps -aq command lists all the containers, including the ones in an exited state, and shows only their IDs. The docker rm $(docker ps -aq) command will remove all the containers, including the ones in an exited state, by passing their IDs to the rm option. This will allow the administrator to clean up the containers in an exited state. This is the correct command to use to accomplish the task. The other options are incorrect because they either do not exist (docker rm --all or docker rm --state exited) or do not remove the containers (docker images prune *). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 19: Managing Cloud and Virtualization Technologies, page 571.

The command that would address the memory-related issue is kill -9 8321. This command will send a SIGKILL signal to the process with the PID 8321, which is the mysqld process that is using 99.7% of the available memory according to the top output. The SIGKILL signal will terminate the process immediately and free up the memory it was using. However, this command should be used with caution as it may cause data loss or corruption if the process was performing some critical operations.

The other options are not correct commands for addressing the memory-related issue. The top -p 8321 command will only display information about the process with the PID 8321, but will not kill it or reduce its memory usage. The renice -10 8321 command will change the priority (niceness) of the process with the PID 8321 to -10, which means it will have a higher scheduling priority, but this will not affect its memory consumption. The free 8321 command is invalid because free does not take a PID as an argument; free only displays information about the total, used, and free memory in the system. References: How to troubleshoot Linux server memory issues; kill(1) - Linux manual page