XK0-005 Practice Test 31 — 15 Questions

Question 1

After a system update, a custom application no longer runs due to a shared library error. The library exists on the system but is in a non-standard path. Which environment variable should be checked or set to resolve this?

Accepted Answer

LD_LIBRARY_PATH. Option C is correct because the LD_LIBRARY_PATH environment variable tells the dynamic linker (ld.so) where to search for shared libraries before the standard system paths. When a custom application fails with a shared library error after an update, and the library exists in a non-standard path, setting LD_LIBRARY_PATH to include that path resolves the issue by allowing the linker to find the library at runtime.

Answer

LD_PRELOAD

Answer

PATH

Answer

LD_RUN_PATH

Question 2

Which TWO commands can be used to display the current kernel version on a Linux system?

Accepted Answer

uname -r. The `uname -r` command displays the kernel release version, which is the standard way to quickly check the current kernel version. The `cat /proc/version` command reads the /proc/version file, which contains a string that includes the kernel version, compiler information, and build date, making it another reliable method to view the kernel version.

Answer

modinfo

Answer

lsmod

Answer

dmesg

Question 3

A database server is running slow. The administrator uses iostat and notices high await times on the disk. Which of the following best explains the implication of high await?

Accepted Answer

Disk I/O requests are taking a long time to complete.. In iostat, 'await' measures the average time (in milliseconds) for I/O requests to be served by the disk, including time spent in the queue and the actual service time. A high await value indicates that disk I/O requests are taking a long time to complete, which directly explains the database server's slowness due to disk latency.

Answer

The CPU is waiting too long for memory access.

Answer

The disk is almost full, causing fragmentation.

Answer

The network filesystem is experiencing latency.

Question 4

A Linux system fails to boot with the error 'No bootable device found'. Which two troubleshooting steps should be taken? (Select TWO).

Accepted Answer

Verify the GRUB configuration. The error 'No bootable device found' indicates that the system's BIOS/UEFI cannot locate a valid bootloader or operating system on any available storage device. Verifying the boot order in BIOS/UEFI (Option E) ensures that the correct disk is set as the first boot device, which is a common cause of this error. Checking the GRUB configuration (Option D) is also critical because if GRUB is missing, corrupted, or misconfigured, the system will not find a bootable kernel, even if the disk is correctly detected.

Answer

Check the SATA cable connections

Answer

Reinstall the kernel

Answer

Run fsck on the root filesystem

Question 5

A system administrator is investigating why a particular process is not responding. They run strace on the process but get no output. What could be the most likely reason?

Accepted Answer

The administrator does not have permission to trace that process.. The most likely reason strace produces no output is that the administrator lacks the necessary permissions to trace the process. By default, strace uses the ptrace system call, which requires either root privileges or the same user ID as the target process, and the process must not have the `dumpable` attribute set to 0 (e.g., via prctl(PR_SET_DUMPABLE, 0)). Without proper permissions, strace fails silently or returns an error like 'Operation not permitted' depending on the output configuration.

Answer

The process is already being traced by another strace instance.

Answer

The process is a kernel thread.

Answer

The process is a zombie process.

Question 6

Which THREE steps should be taken when diagnosing a network connectivity issue where a host cannot reach the internet but can ping the local gateway? (Select three.)

Accepted Answer

Examine the routing table with route -n. Option A is correct because the `route -n` command displays the kernel routing table without resolving hostnames, allowing you to verify whether a default gateway route (0.0.0.0/0) exists. If the host can ping the local gateway but not the internet, a missing or incorrect default route is a common cause, as traffic to external networks would have no path to forward.

Answer

Check ARP cache for the gateway

Answer

Run traceroute to a known external IP

Question 7

A system fails to boot after installing a new SATA disk. The BIOS recognizes the disk. What is the most likely cause?

Accepted Answer

Boot order is incorrect. The most likely cause is an incorrect boot order because the BIOS recognizes the new SATA disk but the system still fails to boot. When a new disk is installed, the BIOS may default to booting from it if it appears earlier in the boot sequence than the original boot device, and if the new disk lacks a bootable operating system, the system will hang or fail to boot. This is a common scenario where the BIOS sees the disk but the boot priority is misconfigured, not a corruption of GRUB or a lack of formatting/partitioning.

Answer

GRUB configuration is corrupted

Answer

The new disk is not formatted

Answer

The new disk is not partitioned

Question 8

A server shows /dev/sda1 mounted at / is 100% full in df -h, but du -sh / shows only 50% usage. What is the most likely explanation?

Accepted Answer

A process is still holding a deleted file open. When a file is deleted but still held open by a running process, the file's inode remains allocated and its disk blocks are not freed until the process closes the file descriptor. The `df` command reports filesystem usage by querying the superblock for total and free blocks, so it still counts the space occupied by the deleted-but-open file. In contrast, `du` traverses the directory tree and sums the sizes of files reachable from the specified path; since the deleted file is no longer linked in the directory, `du` does not include it, leading to the discrepancy.

Answer

The filesystem is corrupted

Answer

Hidden files are not counted by du

Answer

The disk has many hard links

Question 9

A user reports that their home directory is missing after a system reboot. The /home partition is listed in /etc/fstab with an incorrect UUID. What is the most likely outcome?

Accepted Answer

The system will fail to boot entirely. When /etc/fstab contains an incorrect UUID for the /home partition, the systemd-based boot process (or traditional init) will attempt to mount the partition using that UUID. If the UUID does not match any block device, the mount fails. Because /home is not listed with the 'nofail' option in fstab, the boot process treats this as a critical failure and drops into an emergency shell or fails to complete boot, preventing normal login. Option D is correct because an incorrect UUID for a required filesystem causes a boot failure, not a partial mount or a prompt.

Answer

The system will boot normally and mount /home using the device name

Answer

The system will prompt the user to enter the correct UUID

Answer

The system will boot but fail to mount /home

Question 10

A service fails to start and journalctl shows 'Permission denied'. What should the administrator check first?

Accepted Answer

SELinux contexts and file permissions. The 'Permission denied' error in journalctl for a service failure typically indicates that the service process lacks the necessary permissions to access a file, directory, or resource. SELinux contexts and file permissions are the most common causes, as SELinux enforces mandatory access controls (MAC) that can block access even when standard Unix permissions are correct. Checking these first aligns with the troubleshooting principle of verifying access controls before other layers like network or package integrity.

Answer

Package integrity

Answer

DNS resolution

Answer

Firewall rules

Question 11

A Linux engineer is troubleshooting a cron job that does not execute as expected. The crontab entry reads: '*/5 * * * * /usr/local/bin/backup.sh'. The script runs manually when executed as root. Which of the following is the most likely cause?

Accepted Answer

The script requires environment variables that are not set in cron's shell.. D is correct because cron jobs run in a minimal shell environment (typically /bin/sh) with a very limited set of environment variables. The script /usr/local/bin/backup.sh may rely on variables like PATH, HOME, or custom variables that are not set in cron's shell, causing it to fail even though it runs fine manually as root. This is a classic cron issue where the interactive shell's environment differs from cron's non-interactive environment.

Answer

The cron daemon is not running.

Answer

The script file does not have execute permissions.

Answer

The system clock is incorrect.

Question 12

Refer to the exhibit. A user wants to execute the script 'script.sh' but receives a 'Permission denied' error. Which action should be taken to allow execution?

Accepted Answer

Add execute permission with chmod +x script.sh. The 'Permission denied' error indicates the script lacks the execute permission for the user. The `chmod +x script.sh` command adds the execute permission bit to the file's mode, allowing the user to run it as a program. This is the direct and correct fix for the issue.

Answer

Change the owner to the user with chown

Answer

Change the group to the user's primary group

Answer

Set the permissions to 644 with chmod

Question 13

A user reports that their system is unable to boot after a recent kernel update. The system displays a 'kernel panic' message. Which of the following is the MOST efficient way to boot into a previous kernel version?

Accepted Answer

Select an older kernel from the GRUB menu. The GRUB bootloader stores multiple kernel versions after an update, allowing you to select a previous kernel from its menu at boot time. Choosing an older kernel bypasses the faulty new kernel without requiring additional tools or recovery media, making it the most efficient method to resolve a kernel panic caused by a recent update.

Answer

Use the systemd rescue mode

Answer

Reinstall the operating system

Answer

Boot from a live CD and chroot

Question 14

A Kubernetes pod has a container that fails with CrashLoopBackOff. The administrator runs 'kubectl logs pod-name' but sees no output. What is the most likely cause?

Accepted Answer

The container exited before writing to stdout, and logs need to be retrieved with 'kubectl logs --previous'.. When a container enters CrashLoopBackOff, it restarts repeatedly. If 'kubectl logs pod-name' shows no output, it means the current (restarted) container has not written anything to stdout yet. The previous instance of the container may have written logs before crashing, and those logs are accessible using 'kubectl logs --previous' to retrieve the output from the terminated container.

Answer

The container has no logging driver configured.

Answer

The log file is rotated and deleted.

Answer

The pod is not scheduled on any node.

Question 15

A company uses a Linux server running a web application. Users report that they cannot access the website. The administrator checks the web server status and finds it is not running. Which command should the administrator use to view the reason for the service failure?

Accepted Answer

journalctl -xe. The `journalctl -xe` command displays the systemd journal log with the `-x` flag adding explanatory context and `-e` jumping to the end of the log, which is the most direct way to view the reason a systemd-managed service like httpd failed. Since the web server is managed by systemd, its failure reason (e.g., exit code, segfault, configuration error) is recorded in the journal, and this command retrieves that specific failure detail without requiring manual log file parsing.

Answer

systemctl status httpd --full

Answer

tail -f /var/log/httpd/access_log

Answer

dmesg | grep httpd