XK0-006 Practice Test 33 — 15 Questions

Question 1

A cron job that runs a backup script at 2 AM has not been executing. The syslog shows no errors from cron. What is the most likely reason the job is not running?

Accepted Answer

The cron daemon (crond) is not running. The most likely reason is that the cron daemon (crond) is not running. Cron jobs are executed by the cron daemon, which must be active in the background to read the crontab files and launch scheduled tasks. If crond is stopped or not started, no cron jobs will run, and syslog may not show cron-related errors because the daemon is not logging activity.

Answer

The system time zone is incorrect

Answer

The filesystem is full

Answer

The script has incorrect permissions

Question 2

A Bash script uses getopts to parse command-line options. The options are -a (requires an argument) and -b (flag). Which code correctly implements this and stores the argument for -a in $optarg?

Accepted Answer

while getopts 'a:b' opt; do
  case $opt in
    a) arg=$OPTARG ;;
    b) flag=true ;;
  esac
done. The getopts built-in parses options and stores the option argument in the shell variable OPTARG (uppercase). The option string 'a:b' indicates that -a requires an argument (colon after a) and -b is a flag (no colon). The loop uses 'opt' as the variable to hold the current option, and the case statement correctly assigns $OPTARG to arg for -a. This matches option A.

Answer

while getopts 'ab:' opt; do
  case $opt in
    a) arg=$OPTARG ;;
    b) flag=true ;;
  esac
done

Answer

while getopts 'a:b' opt; do
  case $opt in
    a) arg=$optarg ;;
    b) flag=true ;;
  esac
done

Answer

while getopts ':a:b' opt; do
  case $opt in
    a) arg=$OPTARG ;;
    b) flag=true ;;
  esac
done

Question 3

Match each Linux package manager to its distribution family.

Accepted Answer

apt: Debian-based distributions. Different Linux distributions use different package managers: apt is for Debian-based, yum/dnf for Red Hat-based, and pacman for Arch Linux. Common confusions include mixing apt with Red Hat or yum with Arch.

Answer

apt: Red Hat-based distributions

Answer

yum: Arch Linux

Question 4

Match each Linux access control mechanism to its description.

Accepted Answer

DAC: File owners set permissions for their own files.. Correct matches: DAC relates to owner-set permissions; MAC involves system-wide policy enforcement; RBAC uses roles; ACLs extend permissions to multiple users/groups. Common confusions include swapping DAC and MAC definitions, or confusing DAC with RBAC.

Answer

DAC: Access is granted based on user roles.

Answer

MAC: File owners set permissions for their own files.

Question 5

A configuration-management script must take a YAML inventory file and convert it into JSON so a downstream API can consume it, preserving all nested structure. Which command accomplishes this most directly?

Accepted Answer

yq -o=json '.' inventory.yaml. Structured conversion requires a tool that understands YAML syntax, and yq does exactly that by parsing the document and emitting JSON when given the -o=json flag. Text utilities such as sed, grep, and awk operate line by line and cannot reconstruct nested maps and sequences, so they inevitably corrupt the data the API expects.

Answer

awk -F': ' '{print $2}' inventory.yaml

Answer

grep -E '^[a-zA-Z]+:' inventory.yaml

Answer

sed 's/:/=/g' inventory.yaml

Question 6

Refer to the exhibit. An administrator wants to optimize a server running a high-throughput database application. Which command should be used to apply the recommended profile?

Accepted Answer

sudo tuned-adm profile throughput-performance. The tuned-adm recommend command suggests 'throughput-performance', which is suitable for database workloads. The correct command to apply it is 'tuned-adm profile throughput-performance'.

Answer

sudo tuned-adm profile balanced

Answer

sudo tuned-adm off

Answer

sudo systemctl set-default tuned

Question 7

A server is experiencing intermittent high load. The administrator suspects a memory leak in a service. Which sysfs file should the administrator monitor to track memory usage per cgroup?

Accepted Answer

/sys/fs/cgroup/memory/memory.usage_in_bytes. Memory.usage_in_bytes in the cgroup v1 memory hierarchy shows the current memory consumption of processes within a specific cgroup, making it the direct metric to monitor for a suspected memory leak in a service. Unlike system-wide files, this per-cgroup file reflects only the memory used by the service's control group, allowing precise tracking of growth over time.

Answer

/sys/fs/cgroup/memory/memory.limit_in_bytes

Answer

/proc/meminfo

Answer

/sys/fs/cgroup/memory/memory.stat

Question 8

A shared directory requires that any new files created within it are automatically writable by the group. What umask value should be set for users working in this directory?

Accepted Answer

0002. (0002) is correct because the umask subtracts permissions from the default 0666 for files. A umask of 0002 removes the 'write' permission for others (o-w), leaving the group with read/write (rw) and the owner with read/write (rw). This ensures new files are group-writable, as required for a shared directory.

Answer

0777

Answer

0027

Answer

0022

Question 9

After a system update, a server takes significantly longer to boot. The administrator wants to identify which systemd service is causing the delay. Which command provides a detailed analysis of boot time spent by each service?

Accepted Answer

systemd-analyze blame. The `systemd-analyze blame` command prints a list of all running systemd units, sorted by the time they took to initialize during boot. This directly answers the administrator's need to identify which specific service is causing the delay, as it shows the exact time spent by each service.

Answer

systemd-analyze time

Answer

systemd-analyze critical-chain

Answer

systemd-analyze plot

Question 10

An administrator needs to replace all occurrences of 'oldhost' with 'newhost' in the file /etc/hosts. Which sed command should be used?

Accepted Answer

sed -i 's/oldhost/newhost/g' /etc/hosts. sed -i 's/oldhost/newhost/g' /etc/hosts performs an in-place substitution globally.

Answer

sed -e 's/oldhost/newhost/' /etc/hosts

Answer

sed -n 's/oldhost/newhost/gp' /etc/hosts

Answer

sed 's/oldhost/newhost/' /etc/hosts

Question 11

A Linux server runs a critical service managed by a systemd service unit. The administrator needs to configure the service to automatically restart if it crashes, but only up to 3 times within a 30-second window. If the service restarts more than 3 times in 30 seconds, systemd should stop attempting to restart and leave the service in a failed state. Which set of directives should be added to the [Service] section of the unit file to achieve this behavior?

Accepted Answer

`Restart=on-failure` and `StartLimitBurst=3` and `StartLimitIntervalSec=30`. It uses `Restart=on-failure` to trigger a restart only when the service crashes (not on other stops), combined with `StartLimitBurst=3` and `StartLimitIntervalSec=30` to limit restarts to 3 attempts within a 30-second window. When the burst limit is exceeded, systemd automatically places the unit in a failed state, exactly matching the requirement.

Answer

`Restart=on-abort` and `MaxStartups=3`

Answer

`Restart=on-failure` and `StartLimitBurst=5` and `StartLimitIntervalSec=60`

Answer

`Restart=always` and `RestartSec=10`

Question 12

Which TWO characteristics apply to Docker containers compared to virtual machines? (Choose two.)

Accepted Answer

Containers share the host kernel. Option A is correct because Docker containers share the host operating system's kernel rather than booting their own, using namespaces and cgroups for process and resource isolation, which is why they are lightweight compared to VMs. Option B is correct because containers start in milliseconds to seconds since they launch a process directly on the shared kernel instead of booting a full guest OS through a hypervisor. Option C is incorrect because VMs provide stronger isolation via hardware-level virtualization boundaries, whereas containers share the kernel and thus have a weaker security boundary. Option D is incorrect because including a full guest operating system is a characteristic of VMs, not containers. Option E is incorrect because containers run directly on the host kernel via a container runtime such as containerd or runc, not on a hypervisor.

Answer

Containers provide stronger isolation

Answer

Containers include a full guest operating system

Answer

Containers require a hypervisor

Question 13

An administrator wants to gather information about disk usage for a specific directory and its subdirectories. Which TWO commands can be used for this purpose? (Choose two.)

Accepted Answer

du -sh /path. Du reports disk usage for the specified directory and, by default, recurses into its subdirectories, while -s summarizes the total into a single figure and -h presents it in human-readable units. Option D (du -h /path) is also correct because du -h /path likewise walks the directory tree and prints the disk usage of the directory and each subdirectory in human-readable form, satisfying the requirement to gather usage information for the directory and its subdirectories. Option B (df -h /path) is not correct because df reports filesystem-level free and used space for the mount point containing the path, not per-directory or per-subdirectory usage. Option C (ls -lh /path) is not correct because ls only lists file and directory entries with their sizes, without recursively totaling the disk usage of subdirectory contents. Option E (stat /path) is not correct because stat displays metadata such as inode, permissions, and timestamps for a single file or directory, not aggregated disk usage across a directory tree.

Answer

df -h /path

Answer

ls -lh /path

Answer

stat /path

Question 14

A Linux administrator is hardening an SSH server. Which two of the following settings should be applied to /etc/ssh/sshd_config to improve security?

Accepted Answer

PermitRootLogin no. Option C, PermitRootLogin no, is correct because it prevents direct root logins over SSH, forcing administrators to authenticate as an unprivileged user and then escalate privileges via sudo or su, which removes a high-value target and preserves an audit trail. Option D, PasswordAuthentication no, is correct because disabling password authentication forces the use of SSH key pairs (or another stronger method), eliminating brute-force and credential-guessing attacks against user passwords. Option A, Port 2222, merely changes the listening port and is security through obscurity—it does not fix any authentication weakness and can be scanned just as easily. Option B, X11Forwarding yes, is wrong because enabling X11 forwarding expands the attack surface and should typically be set to no on a hardened server. Option E, Protocol 1, is wrong because SSH protocol 1 is deprecated and cryptographically broken; modern sshd_config uses only protocol 2 (and the Protocol directive is obsolete in current OpenSSH).

Answer

Port 2222

Answer

X11Forwarding yes

Answer

Protocol 1

Question 15

A system administrator needs to run a script every 15 minutes. Which systemd unit type is used to schedule this?

Accepted Answer

systemd timer. Systemd timers are the native systemd unit type for scheduling tasks at specified intervals, such as every 15 minutes. They replace traditional cron jobs in systemd-based Linux distributions and are defined with a .timer unit file that triggers a corresponding .service unit. This makes option A correct because the question explicitly asks for the systemd unit type used for scheduling.

Answer

at job

Answer

anacron

Answer

cron job