XK0-006 Practice Test 4 — 10 Questions

Question 1

An administrator is troubleshooting a service that fails to start. They want to trace the system calls made by the service binary. Which command should they use?

Accepted Answer

strace. strace traces system calls and signals. It is used to debug what a program is doing at the kernel level.

Answer

ltrace

Answer

dmesg

Answer

lsof

Question 2

In a Bash script, the administrator wants to capture the output of a command into a variable. Which syntax should be used?

Accepted Answer

$(command). Command substitution can be done with $(command) or backticks `command`. The latter is deprecated. $(( )) is for arithmetic expansion. $VAR is for variable expansion.

Answer

$VAR

Answer

$((command))

Answer

`command`

Question 3

A Linux administrator wants to check the history of CPU usage for the past two days using the system activity reporter. Which sar option retrieves data from the daily history file for a specific date?

Accepted Answer

sar -f /var/log/sa/sa$(date +%d --date='2 days ago'). sar -f /var/log/sa/saDD reads from the history file for a specific day (DD is the day of month).

Answer

sar -r -b

Answer

sar -n DEV

Answer

sar -u -s 00:00:00 -e 23:59:59

Question 4

A technician wants to capture network traffic to analyze a web server issue. Using tcpdump, which THREE options are useful for writing the capture to a file and avoiding name resolution? (Choose three.)

Accepted Answer

-n. -w writes to file, -n avoids name resolution, and -i specifies interface.

Answer

-c 100

Answer

-v

Question 5

A systems administrator needs to ensure that a custom service runs with a specific priority on a Linux server. Which command should the administrator use to achieve this?

Accepted Answer

nice -n -10 /usr/local/bin/myservice. The `nice` command adjusts the CPU scheduling priority of a process at launch time. Using `nice -n -10` sets a higher priority (lower nice value) for the new service, ensuring it runs with the specified priority from the start. This directly meets the requirement to run a custom service with a specific priority.

Answer

renice -10 -p 1234

Answer

ionice -c 2 -n 0 -p 1234

Answer

chrt -r 99 /usr/local/bin/myservice

Question 6

An administrator needs to run a script '/usr/local/bin/cleanup.sh' every day at 2:30 AM. Which crontab entry is correct?

Accepted Answer

30 2 * * * /usr/local/bin/cleanup.sh. The correct crontab syntax is `minute hour day month weekday command`. Option D specifies minute 30, hour 2, and asterisks for all other fields, which means the script runs at 2:30 AM every day. This matches the requirement exactly.

Answer

2 30 * * * /usr/local/bin/cleanup.sh

Answer

*/30 2 * * * /usr/local/bin/cleanup.sh

Answer

30 * * * * /usr/local/bin/cleanup.sh

Question 7

After modifying the network configuration on a RHEL 8 system using NetworkManager, what command should be used to apply the changes without restarting the network service?

Accepted Answer

nmcli con up 'System eth0'. nmcli con up <connection> activates the connection with new settings. nmcli connection reload reloads from disk but does not apply to active connections.

Answer

nmcli connection reload

Answer

ifup eth0

Answer

systemctl restart NetworkManager

Question 8

During boot, the system drops into an emergency target. Which command can be used to repair the root filesystem from this environment?

Accepted Answer

fsck /dev/sda1. In emergency mode, the root filesystem is often mounted read-only. fsck can check and repair filesystems, but requires the filesystem to be unmounted.

Answer

mount -o remount,rw / && fsck /

Answer

xfs_repair /dev/sda1

Answer

journalctl -xb

Question 9

A system administrator configures PAM to enforce account lockout after 3 failed login attempts. Which PAM module should be used?

Accepted Answer

pam_faillock. pam_faillock is the correct PAM module for enforcing account lockout after a specified number of failed login attempts. It tracks failed authentication attempts per user and can lock the account when the threshold (e.g., 3 attempts) is reached, typically by writing to a tally file like /var/log/faillock.

Answer

pam_pwquality

Answer

pam_securetty

Answer

pam_unix

Question 10

Given the journalctl output for the httpd service, which of the following is the most likely cause?

Accepted Answer

The /var/www directory is missing the execute (x) permission for the Apache user. The journalctl output for the httpd service likely shows 'Permission denied' errors when Apache tries to serve files from /var/www. The most common cause is that the /var/www directory lacks the execute (x) permission for the Apache user (typically 'apache' or 'www-data'). Without execute permission on the directory, Apache cannot traverse into it to access files, even if the files themselves have correct permissions. This is a standard Linux permission issue distinct from SELinux or file-level read permissions.

Answer

The file /var/www/html/index.html has incorrect SELinux context

Answer

The Apache service is running under the wrong user

Answer

The file /var/www/html/index.html is missing read permission for the Apache user