CompTIA Linux+ (XK0-006) Practice Tests

Explanation

SSSD (System Security Services Daemon) is the modern standard for integrating Linux systems with Active Directory. SSSD acts as a central broker between the operating system and identity/authentication providers including Active Directory, LDAP, and Kerberos. It supports credential caching for offline login, which is critical when domain controllers are temporarily unreachable. The 'realm join' command simplifies joining a Linux system to an Active Directory domain and configures SSSD automatically. SSSD integrates with PAM and NSS, enabling AD users to log in and be recognized by system tools. pam_unix with /etc/shadow is for local users only and cannot integrate with Active Directory. A direct OpenLDAP client configuration using /etc/nsswitch.conf provides name lookup but lacks credential caching for offline access and does not natively handle Kerberos ticket exchange. NIS is a legacy protocol that is not compatible with Active Directory and has significant security weaknesses.

Explanation

To persist kernel parameters, the administrator should modify /etc/sysctl.conf or create a drop-in file in /etc/sysctl.d/ with a .conf extension. Writing directly to /proc/sys/ files applies changes immediately but they are lost on reboot because /proc is a virtual filesystem. The command sysctl --system applies all drop-in configuration files from /etc/sysctl.d/, /run/sysctl.d/, and /usr/lib/sysctl.d/, as well as /etc/sysctl.conf, making it the correct command to apply all persistent configurations without rebooting. The command sysctl -p only reads /etc/sysctl.conf by default and does not process /etc/sysctl.d/ drop-in files. Modifying /etc/security/limits.conf affects per-user resource limits managed by PAM, not kernel-level parameters like ip_forward.

Explanation

Ansible's notify and handler mechanism is specifically designed for this use case. A task (such as copying a configuration template) can notify a named handler. The handler only executes if the notifying task reports a changed status — meaning the file actually changed. If the template content is identical to the existing file, no change is reported and the handler does not run. This prevents unnecessary restarts. Using a when conditional on the restart task would require manually tracking state and is not idiomatic Ansible. Using register and checking changed status manually is more verbose and error-prone than the notify/handler pattern. Setting the service task with state=restarted unconditionally would restart nginx on every playbook run regardless of whether the configuration changed, causing unnecessary service interruptions.

Explanation

A squash merge combines all commits from the feature branch into a single new commit on the target branch. The git merge --squash feature-branch command stages all changes from the feature branch but does not automatically create a commit, so a subsequent git commit is required to create the single summary commit. This produces a linear history without merge commits while consolidating multiple development commits (including work-in-progress messages like 'fix typo' or 'WIP') into one meaningful commit. The result is a clean main branch history where each feature appears as a single atomic commit. Using git merge --no-ff explicitly creates a merge commit, which is the opposite of the desired linear history. Running git rebase feature-branch from main replays the main branch's commits on top of the feature branch, which is not the correct rebase direction and would complicate the workflow. Cherry-pick selectively copies individual commits and is used for specific scenarios rather than complete feature integration, and would require picking each commit individually.

Explanation

The lvextend command with the -r flag (resize) automatically resizes the filesystem after extending the logical volume, combining both operations in a single command. This works for XFS filesystems and is the most efficient approach. The first option attempts to use xfs_growfs with a device path instead of a mount point, which is incorrect since xfs_growfs requires the filesystem mount point, not the device path. The third option uses resize2fs which is for ext4 filesystems, not XFS. The fourth option incorrectly mixes vgextend syntax with lvextend options; vgextend adds physical volumes to a volume group, not extends logical volumes.