CompTIA XK0-005 Online Practice Questions and Exam Preparation

CompTIA XK0-005 Online Questions & Answers

• Question 301:

  A systems administrator needs to verify whether the built container has the app.go file in its root directory. Which of the following can the administrator use to verify the root directory has this file?

  A. docker image inspect
  B. docker container inspect
  C. docker exec ls
  D. docker ps
  C. docker exec ls

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  Explanation

  The docker exec ls command can be used to verify whether the built container has the app.go file in its root directory. This command will run the ls command inside the specified container and list the files and directories in its root directory. If the app.go file is present, it will be displayed in the output. The docker image inspect command will display information about an image, not a container, and it will not list the files inside the image. The docker container inspect command will display information about a container, not its files. The docker ps command is invalid, as ps does not accept a container name as an argument.

  References: CompTIA Linux+ (XK0- 005) Certification Study Guide, Chapter 16: Virtualization and Cloud Technologies, page 499.

• Question 302:

  A Linux administrator is testing a web application on a laboratory service and needs to temporarily allow DNS and HTTP/HTTPS traffic from the internal network. Which of the following commands will accomplish this task?

  A. firewalld -- add-service=dns, http,https -- zone=internal
  B. iptables -- enable-service='dns|http|https' -- zone=internal
  C. firewall-cmd --add-service={dns, http, https} --zone=internal
  D. systemctl mask firewalld --for={dns, http, https} --zone=internal
  C. firewall-cmd --add-service={dns, http, https} --zone=internal

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  Explanation

• Question 303:

  A Linux administrator is creating a user that can run the FTP service but cannot log in to the system. The administrator sets /bin/false as a login shell for the user. When the user tries to run the FTP service, it is rejected with an "invalid shell: / bin/false" message. Which of the following is the best way to resolve the issue?

  A. Change ownership of /bin/false to the FTP user
  B. Add /bin/false entry to the /etc/shells file
  C. Make /bin/false an executable file
  D. Change the user's default shell to /bin/bash
  B. Add /bin/false entry to the /etc/shells file

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  Explanation

  The /etc/shells file contains a list of valid login shells. Since /bin/false is not listed as a valid shell, adding it to the /etc/shells file will resolve the issue and allow the user to run the FTP service without being able to log into the system interactively.

• Question 304:

  A newly hired junior administrator is studying the format of the /var/log/messages file.

  Which of the following commands should the administrator use to preserve the contents of the original file while also creating an identical file in the /home/admin directory?

  A. touch /var/log/messages /home/admin
  B. mv /var/log/messages /home/admin
  C. cat /var/log/messages > /home/admin/messages
  D. ln -s /var/log/messages /home/admin
  C. cat /var/log/messages > /home/admin/messages

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  Explanation

  Comprehensive and Detailed Step-by-Step Explanation:

  cat /var/log/messages > /home/admin/messages copies the file contents while preserving the original file.

  touch only creates an empty file and does not copy contents.

  mv moves the file instead of copying it.

  ln -s creates a symbolic link but does not copy the contents.

  CompTIA Linux+ Official Study Guide, Chapter on Log Management

• Question 305:

  Users report that connections to a MariaDB service are being closed unexpectedly. A systems administrator troubleshoots the issue and finds the following message in /var/log/messages:

  

  Which of the following is causing the connection issue?

  A. The process mysqld is using too many semaphores.
  B. The server is running out of file descriptors.
  C. Something is starving the server resources.
  D. The amount of RAM allocated to the server is too high.
  B. The server is running out of file descriptors.

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  Explanation

  The message in /var/log/messages indicates that the server is running out of file descriptors. A file descriptor is a non-negative integer identifier for an open file in Linux. Each process has a table of open file descriptors where a new entry is appended upon opening a new file. There is a limit on how many file descriptors a process can open at a time, which depends on the system configuration and the user privileges. If a process tries to open more files than the limit, it will fail with an error message like "Too many open files". This could cause connections to be closed unexpectedly or other problems with the application. The other options are not correct causes for the connection issue. The process mysqld is not using too many semaphores, which are synchronization mechanisms for processes that share resources. Semaphores are not related to file descriptors or open files. Something is not starving the server resources, which could mean high CPU usage, memory pressure, disk I/O, network congestion, or other factors that affect performance. These could cause slowdowns or timeouts, but not file descriptor exhaustion. The amount of RAM allocated to the server is not too high, which could cause swapping or paging if it exceeds the physical memory available. This could also affect performance, but not file descriptor availability.

  References: File Descriptor Requirements (Linux Systems); Limits on the Number of Linux File Descriptors

• Question 306:

  An administrator needs to make an application change via a script that must be run only in console mode. Which of the following best represents the sequence the administrator should execute to accomplish this task?

  A. systemct1 isolate multi-user.target sh script.sh systemct1 isolate graphical.target
  B. systemct1 isolate graphical.target sh script.sh systemct1 isolate multi-user.target
  C. sh script.sh systemct1 isolate multi-user.target systemct1 isolate graphical.target
  D. systemct1 isolate multi-user.target systemct1 isolate graphical.target sh script.sh
  A. systemct1 isolate multi-user.target sh script.sh systemct1 isolate graphical.target

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  Explanation

  The correct answer is A. systemctl isolate multi-user.target sh script.sh systemctl isolate graphical.target This sequence will allow the administrator to switch from the graphical mode to the console mode, run the script, and then switch back to the graphical mode. The systemctl command is used to control the systemd system and service manager, which manages the boot targets and services on Linux systems. The isolate subcommand starts the unit specified on the command line and its dependencies and stops all others. The multi-user.target is a boot target that provides a text-based console login, while the graphical.target is a boot target that provides a graphical user interface. By using systemctl isolate, the administrator can change the boot target on the fly without rebooting the system. The sh command is used to run a shell script, which is a file that contains a series of commands that can be executed by the shell. The script.sh is the name of the script that contains the application change that the administrator needs to make. By running sh script.sh, the administrator can execute the script in the console mode. The other options are incorrect because:

  B. systemctl isolate graphical.target sh script.sh systemctl isolate multi-user.target This sequence will switch from the console mode to the graphical mode, run the script, and then switch back to the console mode. This is not what the administrator wants to do, as the script must be run only in console mode.

  C. sh script.sh systemctl isolate multi-user.target systemctl isolate graphical.target This sequence will run the script in the current mode, which may or may not be console mode, and then switch to console mode and back to graphical mode.

  This is not what the administrator wants to do, as the script must be run only in console mode.

  D. systemctl isolate multi-user.target systemctl isolate graphical.target sh script.sh This sequence will switch from graphical mode to console mode

  and then back to graphical mode, without running the script at all. This is not what the administrator wants to do, as the script must be run only in console mode.

  References:

  systemctl(1) - Linux manual page

  How to switch between the CLI and GUI on a Linux server How to PROPERLY boot into single user mode in RHEL/CentOS 7/8 Changing Systemd Boot Target in Linux Exit Desktop to Terminal in Ubuntu 19.10

• Question 307:

  DRAG DROP

  You have been asked to parse a log file of logins to determine various information about who is logging in and when.

  INSTRUCTIONS

  Open and inspect the Login log file.

  Drag and drop the correct commands onto the output that was generated from that command.

  Tokens can be used only once and not all will be used.

  If at any time you would like to bring back the initial state of the simulation, please click the Reset All button.

  Select and Place:

  

  

• Question 308:

  A Linux administrator needs to create a new cloud.cpio archive containing all the files from the current directory. Which of the following commands can help to accomplish this task?

  A. ls | cpio -iv > cloud.epio
  B. ls | cpio -iv < cloud.epio
  C. ls | cpio -ov > cloud.cpio
  D. ls cpio -ov < cloud.cpio
  C. ls | cpio -ov > cloud.cpio

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  Explanation

  The command ls | cpio -ov > cloud.cpio can help to create a new cloud.cpio archive containing all the files from the current directory. The ls command lists the files in the current directory and outputs them to the standard output. The | operator pipes the output to the next command. The cpio command is a tool for creating and extracting compressed archives. The -o option creates a new archive and the -v option shows the verbose output. The > operator redirects the output to the cloud.cpio file. This command will create a new cloud.cpio archive with all the files from the current directory. The other options are incorrect because they either use the wrong options (-i instead of -o), the wrong arguments (cloud.epio instead of cloud.cpio), or the wrong syntax (< instead of > or missing |).

  References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 11: Managing Files and Directories, page 351.

• Question 309:

  Application code is stored in Git. Due to security concerns, the DevOps engineer does not want to keep a sensitive configuration file, app . conf, in the repository. Which of the following should the engineer do to prevent the file from being uploaded to the repository?

  A. Run git exclude app. conf.
  B. Run git stash app. conf.
  C. Add app . conf to . exclude.
  D. Add app . conf to . gitignore.
  D. Add app . conf to . gitignore.

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  Explanation

  This will prevent the file app.conf from being tracked by Git and uploaded to the repository. The .gitignore file is a special file that contains patterns of files and directories that Git should ignore. Any file that matches a pattern in the .gitignore

  file will not be staged, committed, or pushed to the remote repository. The .gitignore file should be placed in the root directory of the repository and committed along with the other files.

  The other options are incorrect because:

  A. Run git exclude app.conf

  This is not a valid Git command. There is no such thing as git exclude. The closest thing is git update-index --assume-unchanged, which tells Git to temporarily ignore changes to a file, but it does not prevent the file from being uploaded to the repository.

  B. Run git stash app.conf

  This will temporarily save the changes to the file app.conf in a stash, which is a hidden storage area for uncommitted changes. However, this does not prevent the file from being tracked by Git or uploaded to the repository. The file will still be part of the working tree and the index, and it will be restored when the stash is popped or applied.

  C. Add app.conf to .exclude

  This will have no effect, because Git does not recognize a file named .exclude. The only files that Git uses to ignore files are .gitignore, $GIT_DIR/info/exclude, and core.excludesFile.

  References:

  Git - gitignore Documentation

  .gitignore file - ignoring files in Git | Atlassian Git Tutorial Ignoring files - GitHub Docs

  [CompTIA Linux+ Certification Exam Objectives]

• Question 310:

  A systems administrator wants to leverage their password-protected SSH key to connect to multiple servers without entering their password every time. Which of the following commands should the administrator use?

  A. ssh-copy-id
  B. ssh-agent
  C. ssh-add
  D. ssh-keygen
  C. ssh-add

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  Explanation