XK0-006 CompTIA Linux+ V8 Exam Questions and Answers

Package management troubleshooting is an important skill in Linux+ V8, especially on RPM-based distributions that use yum or dnf. When update errors reference a repository, the administrator must verify whether the repository exists and whether it is enabled.

The command yum repolist all displays all configured repositories, including those that are enabled, disabled, or temporarily unavailable. This makes it the most effective command for diagnosing repository-related issues. It allows administrators to quickly confirm the repository’s status and take corrective action, such as enabling it or fixing configuration errors.

The other options are incorrect. yum repo-pkgs manages packages within a repository but does not list repository status. yum list installed repos is not a valid yum command. yum reposync is used to mirror repositories locally and is not intended for verification.

Linux+ V8 documentation highlights yum repolist all as the standard command for repository inspection and troubleshooting.

Therefore, the correct answer is D. yum repolist all.

System boot performance analysis is an important system management task included in Linux+ V8. When administrators need to determine how long services take to start during boot, systemd analysis tools are required.

The correct command is systemd-analyze blame. This command lists all systemd services and shows how long each one took to initialize during the boot process. It is commonly used to identify slow-starting services that may impact system startup performance, including NetworkManager.

The other options are incorrect. resolvectl is used for DNS resolution management and provides no service timing information. journalctl can display logs but does not provide a clear, summarized service startup timing report. systemctl daemon-reload only reloads systemd unit files and does not perform analysis.

Linux+ V8 documentation explicitly references systemd-analyze blame as the correct tool for diagnosing service startup delays. Therefore, the correct answer is D.

When troubleshooting name resolution issues in Linux, /etc/hosts entries take precedence over DNS lookups. The workstation’s /etc/hosts file contains the line:

CopyEdit

104.18.99.101 www.comptia.org

This means any attempt to access www.comptia.org will resolve to 104.18.99.101, regardless of the real DNS response. However, both dig and nslookup show the correct IP as 104.18.16.29. Because the local /etc/hosts entry overrides DNS, and the hardcoded IP is either incorrect or unreachable, all network traffic to www.comptia.org will fail or not reach the intended destination, resulting in the observed connectivity issue (Destination Host Unreachable).

Other options:

B. The lack of IPv6 support is irrelevant since the host is using IPv4 and the DNS queries for IPv4 (A record) are successful.

C. The firewall would block all HTTP/HTTPS connections, but the error shown is a host unreachable, not a port-specific issue.

D. The nameserver is working; both dig and nslookup queries succeed and return the correct A record.

Part 1 – Begin the recovery process

Answer:

vgcfgrestore vg01 -f /etc/lvm/archive/vg01_00001-810050352.vg

Part 2 – Continue the recovery process

Answer:

lvchange -ay /dev/vg01/lv01

Part 3 – Complete recovery and access data

Answer:

mount /dev/vg01/lv01 /important_data

This performance-based question tests LVM recovery, a critical System Management skill in CompTIA Linux+ V8. The scenario indicates that a logical volume was removed, but the underlying physical volume and volume group metadata still exist.

???? Part 1: Restoring Volume Group Metadata

The first screenshot shows that:

Physical volumes (pvdisplay, pvs) still exist

The logical volume is missing

/etc/lvm/archive/ contains archived VG metadata

Linux automatically stores backups of LVM metadata in /etc/lvm/archive whenever changes are made. The correct first step is to restore the volume group metadata using:

vgcfgrestore vg01 -f /etc/lvm/archive/vg01_00001-810050352.vg

This restores the logical volume definitions but does not activate them yet.

This is the only correct starting point in Linux+ V8 recovery workflows.

???? Part 2: Activating the Logical Volume

After metadata restoration:

The LV exists but is inactive

blkid shows the LV as TYPE="LVM2_member"

The logical volume must be activated before it can be mounted:

lvchange -ay /dev/vg01/lv01

This makes the LV available under /dev/vg01/lv01.

Linux+ explicitly requires LV activation after recovery.

???? Part 3: Accessing the Data

The final output shows:

The filesystem type is xfs

The logical volume is now visible

Since there is no indication of filesystem corruption, no repair is required.

The correct final step is to mount the filesystem:

mount /dev/vg01/lv01 /important_data

This restores full access to the underlying data.

This scenario is a classic performance troubleshooting case covered under the Troubleshooting domain of the CompTIA Linux+ V8 objectives. The key indicators to analyze are the load average values and the CPU utilization statistics.

The uptime command shows load averages of 8.71, 8.24, and 7.71 over the 1-, 5-, and 15-minute intervals. Load average represents the average number of processes that are either running on the CPU or waiting to run. On a system with 4 CPU cores, a healthy load average would typically be close to or below 4. Load averages consistently near or above 8 indicate that there are significantly more runnable processes than available CPU resources, causing processes to wait and resulting in poor system responsiveness.

The CPU output further confirms this condition. The %idle value is 0, meaning the CPU has no idle time available. The majority of CPU time is spent in user space (65.88%) and system/kernel space (20.54%), indicating heavy computational and kernel activity. While %iowait is present at 5.65%, it is not high enough to suggest that disk I/O is the primary bottleneck.

Option C, high CPU load, best explains the symptoms. High CPU load causes commands to execute slowly because processes are competing for limited CPU time. This directly matches the observed behavior of the system being unresponsive.

The other options are incorrect. High uptime simply indicates how long the system has been running and does not cause performance issues by itself. High latency is a general term and not a specific diagnosis shown by the metrics provided. High I/O wait times would require a significantly higher %iowait value.

According to Linux+ V8 documentation, correlating load averages with CPU core count and utilization is essential for accurate performance diagnosis. Therefore, the correct answer is C. High CPU load.

User and group management is a core System Management topic in CompTIA Linux+ V8. When adding a user to an additional group—such as the docker group—care must be taken not to alter the user’s primary group.

The correct command is sudo usermod -aG docker user. The -G option specifies a supplementary group, and the -a (append) option ensures the user is added to the group without removing existing group memberships. This is especially important because omitting -a would overwrite the user’s supplementary groups.

Option B, usermod -g docker user, changes the user’s primary group, which is not desired. Options A and D misuse groupmod, which is intended for modifying group properties, not user membership.

Linux+ V8 documentation explicitly warns that failing to use -a with -G can unintentionally remove a user from all other supplementary groups, potentially causing access issues.

Therefore, the correct and safe command is C. sudo usermod -aG docker user.

Comprehensive and Detailed Explanation From Exact Extract:

To temporarily configure a Linux virtual machine as a router, the technician must enable IP forwarding and set up iptables rules to allow and masquerade traffic:

A. echo "1" > /proc/sys/net/ipv4/ip_forward: Enables IPv4 forwarding in the Linux kernel, allowing the VM to forward packets between interfaces.

B. iptables -A FORWARD -j ACCEPT: Adds a rule to the iptables firewall to accept all forwarded packets (allows traffic to be routed).

G. iptables -t nat -s 10.10.204.0/24 -A POSTROUTING -j MASQUERADE: Sets up network address translation (NAT) for outgoing packets from the 10.10.204.0/24 subnet, masquerading them as if they are coming from the VM’s external IP.

Other options:

C. and H. are not relevant for routing/NAT in this context (PREROUTING is generally used for DNAT, not for standard source NAT).

D. is syntactically incorrect and mixes PREROUTING with MASQUERADE, which is not the proper combination for SNAT.

E. disables forwarding.

F. is not related to IP forwarding.

Comprehensive and Detailed Explanation From Exact Extract:

During SSH public key authentication, the server checks if the user's public key is present in the ~/.ssh/authorized_keys file. If the key is found, the server uses it to verify the user's identity by sending a challenge that can only be answered by the corresponding private key. This process does not involve password hashing or using the public key directly for encryption of the communication stream. Instead, the public key is simply used as a reference for authentication.

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 issue falls under the Troubleshooting domain of the CompTIA Linux+ V8 objectives, specifically service startup failures and certificate-related errors. The provided output clearly indicates that the NGINX service fails during startup due to an inability to locate the private key file.

The critical error message is:

cannot load certificate key "/etc/pki/nginx/private/server.key": No such file or directory

This message confirms that NGINX is explicitly configured to look for the private key in the directory /etc/pki/nginx/private/. However, the directory listing shows that the private directory exists but is empty, while the server.key file is located in /etc/pki/nginx/ instead. Because NGINX cannot find the private key at the configured path, the configuration test (nginx -t) fails, and systemd prevents the service from starting.

Option C correctly identifies the root cause: the private key is not in the correct location. Moving server.key into /etc/pki/nginx/private/ (or updating the NGINX configuration to match the current location) would resolve the issue. Linux+ V8 documentation stresses that service failures often result from misaligned configuration paths rather than corrupted files.

The other options are incorrect. Option A incorrectly refers to renaming a certificate file and does not address the path issue. Option B suggests a key mismatch, which would generate a different SSL error rather than a “file not found” error. Option D is also incorrect because private keys should not have executable permissions like 0755; typically, they are restricted (for example, 0600) for security reasons.

Therefore, the web service is not responding because the private key file is not located in the directory expected by the NGINX configuration. The correct answer is C.

Shell variable expansion is a fundamental scripting concept included in Linux+ V8 objectives. In Bash and similar shells, variables are expanded only when they are interpreted within double quotes or unquoted contexts, and sometimes explicit syntax is required to avoid ambiguity.

The correct notation is ${num}, as shown in option D. Using curly braces around the variable name ensures the shell correctly identifies the variable boundary, especially when it is adjacent to other characters. This guarantees proper expansion of the variable’s value.

The other options are incorrect. Single quotes prevent variable expansion entirely. The $(...) syntax is used for command substitution, not variable expansion. Quoting the variable name itself also prevents expansion.

Linux+ V8 documentation emphasizes ${VAR} notation as a best practice in shell scripting for clarity and correctness. Therefore, the correct answer is D.

For normal users to change their own password, /bin/passwd must have the SUID bit set (permissions should be -rwsr-xr-x). The SUID bit allows users to run the program with the permissions of the file owner (root), which is required to update /etc/shadow. The provided output shows /bin/passwd does not have the SUID bit (no 's' in the owner’s execute field). As a result, user "test" receives an "Authentication token manipulation error". The password can be changed as root, which confirms it's a permissions/SUID issue.

Other options:

B. If the password didn’t meet requirements, a different error would appear.

C. There is no minimum day limit preventing password change (see chage -l output).

D. The account and password are active (not disabled).

Firewall configuration is a key topic in the Security domain of CompTIA Linux+ V8. DNS primarily uses UDP port 53, but TCP port 53 is also required for zone transfers, large responses, and certain reliability scenarios. In this case, the administrator explicitly needs to allow DNS over TCP from a specific network.

The correct command is ufw allow 53/tcp from 10.0.0.0/24. This rule allows incoming TCP traffic on port 53 only from the specified subnet, following the principle of least privilege. Linux+ V8 documentation emphasizes restricting firewall rules by source network whenever possible to minimize attack surfaces.

Option A is incorrect because UFW service aliases like dns are not always guaranteed to map explicitly to TCP, and the syntax is incomplete. Option B is invalid because ufw enable is used to enable the firewall globally and does not define rules. Option D disables firewall protections and introduces a major security risk.

Linux+ V8 best practices stress precise, minimal firewall rules instead of broad or disabling actions. Therefore, C is the correct and secure choice.

Version control rollback operations are a core DevOps skill covered in the Linux+ V8 objectives. When changes in a local Git repository break an application and must be reverted, the administrator must choose a command that directly undoes those changes.

The command git reset is the most appropriate option in this scenario. It allows the engineer to move the current branch pointer (HEAD) to a previous commit, effectively discarding or undoing local changes. Depending on the reset mode (--soft, --mixed, or --hard), the engineer can control whether changes are preserved in the staging area or working directory. This flexibility makes git reset the primary tool for reverting problematic local changes.

The other options are not suitable. git pull fetches and merges changes from a remote repository and does not revert local modifications. git rebase rewrites commit history and is used to reapply commits on top of another base, not to undo broken changes. git stash temporarily saves uncommitted changes for later use but does not revert the repository to a stable state.

Linux+ V8 documentation emphasizes that git reset is commonly used during local development when changes need to be undone quickly before being shared with others. Therefore, the correct answer is B.

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.

Comprehensive and Detailed Explanation From Exact Extract:

The lsscsi command is used to list information about SCSI devices (including storage arrays) that are attached to the system. This is critical when integrating a new storage array because it allows the administrator to verify that the operating system detects the new device at the SCSI layer, which is the underlying interface for most enterprise storage solutions. lsscsi outputs a list of recognized SCSI devices, their device nodes, and associated information.

Other options:

B. lsusb: Lists USB devices, not storage arrays on SCSI/SATA/SAS.

C. lsipc: Displays information on IPC (inter-process communication) facilities, unrelated to hardware detection.

D. lshw: Lists hardware details and can show storage, but lsscsi is specifically designed for SCSI device detection and is the most direct method for this task.

Directory services are a key part of enterprise Linux environments and are covered under the Security domain in Linux+ V8. The Lightweight Directory Access Protocol (LDAP) is specifically designed to access and manage distributed directory information.

LDAP directories store structured, hierarchical data such as users, groups, computers, and organizational units. Linux systems commonly use LDAP for centralized authentication, authorization, and identity management. LDAP is also the foundation for services like Active Directory and FreeIPA.

The other options are incorrect. SMB is a file and printer sharing protocol. TLS is an encryption protocol used to secure communications. Kerberos (KRB-5) is an authentication protocol often used alongside LDAP but does not store directory information itself.

Linux+ V8 documentation highlights LDAP as the primary protocol for directory-based identity services. Therefore, the correct answer is C.

Container management and image handling are part of modern Linux automation practices covered in CompTIA Linux+ V8. Docker images are stored in container registries such as Docker Hub, and administrators commonly need to download images to deploy containers.

The correct command for downloading an image from a Docker repository is docker image pull. This command retrieves the specified image from a configured container registry and stores it locally. When no tag is specified, Docker automatically pulls the latest available version of the image. Therefore, docker image pull debian downloads the most recent Debian image from Docker Hub.

The other options are incorrect. docker image init is not a valid Docker command and does not exist in Docker’s CLI. docker image import is used to create a Docker image from a tarball file, not to download an image from a repository. docker image save exports an existing local image into a tar archive and does not retrieve images from a remote registry.

Linux+ V8 documentation emphasizes understanding container image lifecycles, including pulling, tagging, and running images. Pulling images is a foundational step before container execution and automation workflows.

Therefore, the correct answer is B. docker image pull debian.

Comprehensive and Detailed Explanation From Exact Extract:

To add an existing user (myuser) to an existing group (finance) without removing them from other groups, the correct command is usermod -aG finance myuser. The -aG option appends the user to the supplementary group(s) specified.

Other options:

A. groupadd is for creating new groups, not adding users to groups.

B. groupmod is for modifying group properties, not user membership.

C. useradd creates new users; not applicable to existing users.

Disk forensics and malware analysis fall under the Security domain in the CompTIA Linux+ V8 objectives. When analyzing a compromised disk, it is critical to preserve the data exactly as it exists, including unused space, deleted files, and hidden metadata. This requires a block-level copy, not a file-level copy.

The dd command is the correct tool for this task. It operates at a low level, copying raw data from an input device (if=/dev/sdc) directly to an output file (of=/tmp/image) without interpreting filesystem structures. This ensures an exact, bit-for-bit replica of the disk, which is essential for forensic integrity and malware analysis. The bs=8192 option improves performance by specifying a larger block size during copying.

The other options are incorrect. cp -rp copies files and directories but does not capture free space, deleted data, or disk metadata. cpio and tar are archive utilities that operate at the filesystem level and cannot produce a true disk image. These tools also require the filesystem to be mounted and readable, which is not appropriate for forensic preservation.

Linux+ V8 documentation highlights dd as the preferred utility for disk imaging, backups, and forensic investigations. Administrators are also advised to perform such operations on unmounted disks to avoid altering evidence.

Therefore, the correct and best command for creating an exact block-level disk copy is D. dd if=/dev/sdc of=/tmp/image bs=8192.

The use of AI-assisted tools for Infrastructure as Code (IaC) is increasingly common in modern DevOps practices, which are covered in the Automation and Orchestration domain of CompTIA Linux+ V8. While AI can accelerate code generation, Linux+ emphasizes that generated code must still follow best practices for quality, security, and maintainability.

Option C, linting generated code, is the correct answer. Linting involves analyzing code for syntax errors, style violations, logical issues, and potential security risks before deployment. When AI tools generate IaC artifacts such as Terraform files, Ansible playbooks, or shell scripts, linting ensures that the output adheres to organizational standards and does not introduce misconfigurations or vulnerabilities.

Linux+ V8 documentation stresses that automation does not eliminate the need for validation. Administrators remain responsible for verifying correctness and compliance. Linting tools such as ansible-lint, terraform fmt, and shell linters help detect issues early in the pipeline and prevent faulty infrastructure deployments.

The other options are poor practices. Copying and pasting code increases the risk of errors and inconsistency. Generating monolithic code contradicts modular IaC principles. Merging CI/CD pipelines is unrelated to validating AI-generated infrastructure code.

Therefore, the correct answer is C. Linting generated code.

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.

Comprehensive and Detailed Explanation From Exact Extract:

Reducing the attack surface area in Linux hardening refers to limiting possible points of unauthorized access. According to the CompTIA Linux+ Official Study Guide (Exam XK0-006), enforcing strong password policies is a critical aspect of security hardening. This practice ensures that user accounts are protected by passwords that are difficult to guess or crack, thus minimizing the risk of successful brute-force attacks. Implementing password complexity requirements (such as minimum length, use of uppercase, lowercase, numbers, and special characters) directly addresses one of the primary vectors for unauthorized access.

Other options do not have a direct impact on reducing the attack surface:

A. Customizing the log-in banner serves as a legal notification and does not affect system vulnerabilities.

B. Reducing the number of directories created is not related to hardening or access control.

C. Extending the SSH startup timeout period may give attackers more time to attempt a connection and does not increase security.