XK0-006 Practice Test 40 — 15 Questions

Question 1

Which TWO commands can be used to check the kernel version currently running on a system? (Choose two.)

Accepted Answer

cat /proc/version. The file /proc/version contains the kernel version string, including the version number and compiler information, as maintained by the kernel at boot time. Reading this file with cat displays the exact kernel version currently running on the system.

Answer

sysctl kernel.version

Answer

lsb_release -a

Answer

uptime

Question 2

A developer is writing a Bash script that needs to parse command-line options with arguments, such as -f filename and -v. Which built-in command should be used to handle these options?

Accepted Answer

getopts. getopts is the standard Bash built-in for parsing short options with or without arguments.

Answer

getopt

Answer

case

Answer

shift

Question 3

A technician needs to trace the system calls made by a running process to debug a performance issue. Which tool should be used?

Accepted Answer

strace -p PID. `strace -p PID` intercepts and records system calls (kernel-level operations like file I/O, network, and process control) made by a running process, which is exactly what is needed to trace system calls for debugging performance issues. The `-p` flag attaches strace to an existing process by its PID, allowing real-time monitoring of kernel interactions.

Answer

gdb -p PID

Answer

lsof -p PID

Answer

ltrace -p PID

Question 4

An administrator needs to identify which processes are consuming the most CPU and memory resources. Which two commands can provide this information? (Choose two.)

Accepted Answer

top. Option A, top, is correct because it is an interactive process monitor that displays a live, continuously refreshed list of running processes ranked by CPU usage by default, and it also shows per-process memory (RES/%MEM) so the administrator can identify the top CPU and memory consumers in one view. Option E, ps aux --sort=-%mem, is correct because it produces a static snapshot of all processes (a = all users, u = user-oriented format, x = include processes without a controlling terminal) sorted in descending order by memory percentage, which directly reveals the heaviest memory consumers and, with the aux output, their CPU usage as well. Option B, free -h, is not correct because it only reports aggregate system memory and swap usage in human-readable units, not per-process consumption. Option C, iostat -x, is not correct because it reports extended disk I/O and CPU utilization statistics per device, not which processes are using CPU or memory. Option D, vmstat 1 5, is not correct because it samples system-wide virtual memory, CPU, and I/O statistics every second for five iterations, but it does not attribute resource usage to individual processes.

Answer

free -h

Answer

iostat -x

Answer

vmstat 1 5

Question 5

A system administrator wants to review kernel-related log messages from the current boot session. Which journalctl command should be used to filter the kernel messages?

Accepted Answer

journalctl -k. journalctl -k shows kernel messages from the current boot.

Answer

journalctl -p err

Answer

journalctl -b -u systemd-journald

Answer

journalctl --since today

Question 6

A user reports that they cannot reach a website. The administrator wants to check the path that packets take to the destination server. Which command should be used?

Accepted Answer

traceroute. The `traceroute` command is used to trace the path packets take from the source to a destination host, showing each hop (router) along the way. It uses ICMP echo requests (or UDP packets on Linux) with incrementing TTL values to elicit ICMP Time Exceeded messages from intermediate routers, which reveals the network path. This directly addresses the administrator's need to check the path to the destination server.

Answer

ip addr

Answer

ss

Answer

ping

Question 7

In a bash script, a variable is set as follows: myvar='Hello World'. Which of the following correctly prints the first 5 characters of the variable?

Accepted Answer

echo ${myvar:0:5}. Bash parameter expansion supports substring extraction using the syntax ${variable:offset:length}. With myvar='Hello World', ${myvar:0:5} starts at index 0 and returns 5 characters, yielding 'Hello'. This is the standard, portable way to slice a string in Bash.

Answer

echo ${myvar#?????}

Answer

echo ${myvar:0-5}

Answer

echo ${myvar:5}

Question 8

A Linux administrator writes a script that uses bash-specific features like arrays and process substitution. Which shebang should be used?

Accepted Answer

#!/bin/bash. The correct shebang is #!/bin/bash because the script uses bash-specific features such as arrays and process substitution. The shebang line tells the system to execute the script with the specified interpreter; /bin/bash is the Bourne Again SHell, which supports these features, while /bin/sh may be a POSIX shell that lacks them.

Answer

#!/bin/sh

Answer

#!/usr/bin/python3

Answer

#!/bin/ksh

Question 9

A Linux administrator writes a Bash script and includes the line `#!/bin/bash` at the top. What is the purpose of this line?

Accepted Answer

It specifies the interpreter to execute the script.. The `#!/bin/bash` line is a shebang that tells the operating system which interpreter to use when executing the script. When the script is run as an executable, the kernel reads this line and invokes `/bin/bash` to process the file.

Answer

It sets the script to run in the background.

Answer

It enables debugging mode.

Answer

It defines a variable for the script.

Question 10

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 11

A system is experiencing high load average. The administrator runs 'vmstat 1 5' and sees a high 'wa' value. What does this indicate?

Accepted Answer

High disk I/O wait. The 'wa' column in vmstat output indicates the percentage of time the CPU is waiting for I/O operations to complete. A high 'wa' value means the CPU is idle because it is blocked waiting for disk I/O, which directly points to high disk I/O wait. This is a classic indicator of a storage bottleneck.

Answer

High memory swapping activity

Answer

High CPU usage by user processes

Answer

High network I/O

Question 12

Refer to the exhibit. A technician sees that the httpd service has failed. Which command was used to view the detailed error log shown in the exhibit?

Accepted Answer

journalctl -u httpd. The `journalctl -u httpd` command is correct because it queries the systemd journal for logs specifically associated with the `httpd` unit. The exhibit shows a detailed error log with timestamps, process IDs, and error messages, which is exactly the output format of `journalctl` when filtering by a unit. This command provides the most comprehensive view of the service's recent failures, including kernel and application-level errors.

Answer

systemctl status httpd

Answer

tail -f /var/log/messages

Answer

systemctl show httpd

Question 13

A technician needs to identify the network interface configuration and IP address of a system. Which command provides the most comprehensive output for this task?

Accepted Answer

ip addr show. The `ip addr show` command is the most comprehensive because it displays all network interfaces along with their IP addresses (IPv4 and IPv6), MAC addresses, MTU, state (UP/DOWN), and additional flags. It is part of the modern `iproute2` suite, which is the standard for Linux network configuration and supersedes older tools like `ifconfig`.

Answer

nmcli dev show

Answer

netstat -i

Answer

ifconfig

Answer

hostname -I

Question 14

Which command creates a symbolic link named 'link.txt' that points to 'original.txt'?

Accepted Answer

ln -s original.txt link.txt. ln -s target link_name creates a symbolic link.

Answer

symlink original.txt link.txt

Answer

ln original.txt link.txt

Answer

ln -s link.txt original.txt

Question 15

A junior administrator accidentally modified the /etc/sudoers file and now users report not being able to use sudo. Which command should be used to safely edit the sudoers file?

Accepted Answer

visudo. The `visudo` command is the correct and safe way to edit the `/etc/sudoers` file because it locks the file against concurrent edits, performs syntax validation before saving, and prevents saving a malformed configuration that could break sudo entirely. This ensures that even if the administrator makes a mistake, the original valid file is preserved, avoiding the exact scenario described where users lose sudo access.

Answer

chmod 400 /etc/sudoers

Answer

echo 'user ALL=(ALL) ALL' >> /etc/sudoers

Answer

usermod -aG wheel user