Pass the CompTIA Linux+ XK0-006 Questions and answers with Dumpstech

Password management is a core topic in the Security domain of CompTIA Linux+ V8. Password expiry policies are implemented to reduce the risk associated with long-lived credentials.

The primary reason for enforcing password expiration is to mitigate the risk of exposed or compromised passwords. If a password is leaked through phishing, malware, keylogging, or data breaches, limiting its lifespan reduces the window of opportunity for attackers to exploit it. Requiring periodic password changes ensures that compromised credentials eventually become invalid.

Option B correctly captures this security objective. Linux+ V8 documentation emphasizes minimizing credential exposure as a key principle of access control.

The other options are secondary or incorrect. Avoiding password reuse and increasing complexity are addressed through password history and complexity policies, not expiration alone. Password expiry does not force passwordless authentication, making option C incorrect.

Therefore, the correct answer is B. To mitigate the use of exposed passwords.

In Git-based workflows, especially those used in DevOps environments, it is common for administrators to have uncommitted local changes while needing to retrieve updates from a remote repository. Linux+ V8 emphasizes understanding how to safely manage local modifications during synchronization operations.

The command git stash is specifically designed for this scenario. It temporarily saves (or “stashes”) local changes in a stack-like structure and reverts the working directory to a clean state that matches the current HEAD. This allows the administrator to perform operations such as git pull without conflicts. Later, the stashed changes can be reapplied using git stash apply or git stash pop.

The other options are incorrect. git pull retrieves and merges remote changes but will fail or cause conflicts if local modifications exist. git merge combines branches and does not save uncommitted changes. git fetch downloads remote references but does not address local working directory changes.

Linux+ V8 documentation highlights git stash as a safe and reversible way to protect local work during repository updates. Therefore, the correct answer is A.

This scenario involves shared directory collaboration, which is a common system management task covered in the CompTIA Linux+ V8 objectives. The key issue is that users can create files in the shared directory, but other users in the same group cannot modify those files. This behavior is directly related to group ownership inheritance.

By default, when a user creates a file or directory, it is owned by the user and assigned the user’s primary group, not necessarily the group of the parent directory. As shown in the output, files inside /share are owned by different groups (student, student2, student3), which prevents other group members from modifying them, even though the parent directory is group-writable.

The correct solution is to set the setgid (set group ID) bit on the shared directory, making option D correct. When the setgid bit is applied to a directory, all newly created files and subdirectories inherit the group ownership of the parent directory, rather than the creator’s primary group. This ensures consistent group ownership and allows all members of the shared group to collaborate effectively.

The other options are incorrect or poor practice. Option A (setuid) is intended for executables, not directories. Option B requires constant manual intervention and does not scale. Option C weakens security by granting write access to all users, violating the principle of least privilege.

Linux+ V8 documentation explicitly recommends using the setgid bit on shared directories to manage collaborative access securely and efficiently.

According to the output of getfacl app, user1 has only "rw" (read and write) permissions, but lacks "x" (execute). Without execute permission, user1 cannot run the file. To allow user1 to execute app, you must update the ACL to add execute permission (e.g., setfacl -m u:user1:rwx app). Modifying "others" permissions (option B) is not secure or necessary, adding user1 to the wheel group (option C) is unrelated, and moving the file (option D) does not resolve permission issues.

Filesystem unmount failures are common troubleshooting scenarios covered in Linux+ V8. When the error “target is busy” appears, it means one or more processes are actively using files or directories within the mount point.

The correct diagnostic command is lsof | grep /data1. The lsof (list open files) utility displays all open files and the processes using them. Filtering the output with grep /data1 identifies exactly which processes are holding file descriptors on the filesystem, preventing it from being unmounted.

The other options are incorrect. ps -f displays process information but does not show open file usage. du -sh calculates disk usage and does not identify active processes. top monitors system performance but cannot pinpoint filesystem locks.

Linux+ V8 documentation emphasizes using lsof or fuser to identify resource locks before unmounting filesystems. Therefore, the correct answer is D.

DNS client configuration is a foundational Linux networking task covered in Linux+ V8 system management objectives. When an administrator needs to specify the IP address of a DNS server that the system should use for name resolution, the correct file to modify is /etc/resolv.conf.

The /etc/resolv.conf file defines DNS resolver settings, including one or more nameserver entries that specify the IP addresses of DNS servers. Applications and system services rely on this file to resolve hostnames to IP addresses.

The other options are incorrect. /etc/whois.conf configures WHOIS queries. /etc/nsswitch.conf controls the order of name resolution sources but does not define DNS server IP addresses. /etc/dnsmasq.conf configures a local DNS caching service, not the system-wide resolver directly.

Linux+ V8 documentation highlights /etc/resolv.conf as the authoritative DNS client configuration file, though it may be dynamically managed by tools such as NetworkManager or systemd-resolved.

Therefore, the correct answer is B. /etc/resolv.conf.

Container troubleshooting is a key competency within the Automation, Orchestration, and Scripting domain of CompTIA Linux+ V8. When users report that an application running inside containers is not accessible, one of the first validation steps is to confirm whether the containers are currently running.

The docker ps command is specifically designed to list running containers on the system. By default, it displays container IDs, image names, command executed, uptime, port mappings, and container names. This allows administrators to quickly determine whether the application container is active and whether it is exposing the expected ports. This aligns directly with Linux+ V8 guidance on container lifecycle management and operational validation.

The other options are not suitable for this purpose. docker start is used to start one or more stopped containers but does not display container status. docker run creates and starts a new container, which is not appropriate when the goal is only to check the status of existing containers. docker images lists locally available container images but provides no information about running or stopped containers.

Linux+ V8 documentation emphasizes the importance of using the correct Docker subcommands when diagnosing containerized applications. Verifying container runtime state using docker ps is a foundational troubleshooting step before investigating networking, firewall rules, or application-level errors.

Therefore, the correct command to validate whether containers are running is docker ps, making Answer B correct.

In Linux, the ability to execute a program by typing only its name depends on whether the directory containing the executable is included in the user’s PATH environment variable. The PATH variable defines a colon-separated list of directories that the shell searches when a command is entered.

Option C, export PATH=$PATH:/home/user/scripts, correctly appends the /home/user/scripts directory to the existing PATH variable. Once this command is executed, any executable script located in that directory can be run simply by typing its filename, provided the script has execute permissions. This behavior is explicitly covered in the Linux+ V8 objectives related to environment variables and shell configuration.

The other options are incorrect. Option A incorrectly attempts to redefine the SHELL variable and uses invalid syntax. Option B modifies the TERM variable, which controls terminal type and has nothing to do with command execution. Option D attempts to create an alias using invalid syntax and would not affect command lookup behavior.

Linux+ V8 documentation emphasizes modifying the PATH variable as the standard and recommended method for simplifying script execution. This approach is commonly used by developers and administrators who frequently run custom scripts.

Therefore, the correct answer is C.

This scenario represents a classic DNS troubleshooting situation covered in the Troubleshooting domain of the CompTIA Linux+ V8 objectives. Although the DNS zone file has been updated correctly on the BIND server, the system continues to resolve the domain name to an outdated IP address. This behavior strongly indicates DNS caching rather than a configuration error in the zone file itself.

Modern Linux systems that use systemd-resolved cache DNS responses locally to improve performance and reduce external queries. Even after a DNS record is updated on the authoritative server, cached results may persist until the cache expires or is manually cleared. The nslookup output showing a non-authoritative answer further confirms that the response is being served from a cache rather than directly from the updated zone data.

The correct solution is to flush the local DNS cache so the system can retrieve the updated record from the DNS server. The command resolvectl flush-caches clears all cached DNS entries maintained by systemd-resolved, forcing fresh queries to authoritative name servers. This aligns directly with Linux+ V8 documentation for resolving name resolution inconsistencies caused by stale cache entries.

The other options are incorrect for the following reasons. systemd-resolve query www.abc.com performs a DNS lookup but does not clear cached entries. systemd-resolve status only displays resolver configuration and statistics. service nslcd reload reloads the Name Service LDAP daemon and is unrelated to DNS resolution or caching.

Linux+ V8 emphasizes identifying whether issues originate from services, configuration, or cached data. In this case, flushing the DNS cache is the correct and least disruptive corrective action.

Therefore, the correct answer is D. resolvectl flush-caches.

Comprehensive and Detailed 250 to 350 words of Explanation From Linux+ V8 documents:

Container lifecycle management is a core topic within the Automation, Orchestration, and Scripting domain of CompTIA Linux+ V8. Administrators must understand the difference between creating containers, starting containers, and executing commands within running containers.

The correct command is docker run -it app-01-image. The docker run command performs three actions at once: it creates a new container from the specified image, starts the container, and optionally attaches the administrator’s terminal to it. The -i option keeps standard input open, while the -t option allocates a pseudo-terminal (TTY). Together, these options allow the administrator to interactively connect to the container immediately after it is created.

The other options are incorrect for the following reasons. docker start is used only to start an existing stopped container and does not create a new container from an image. Additionally, -t and -d are not valid options for attaching an interactive terminal during container startup. docker build is used to build a Docker image from a Dockerfile and cannot be used to create or connect to a container. docker exec is used to run commands inside an already running container and therefore cannot be used to create a container.

Linux+ V8 documentation emphasizes that docker run is the primary command used when administrators want to instantiate containers from images and interact with them. This command is commonly used during testing, development, and troubleshooting workflows.