XK0-006 Practice Test 17 — 15 Questions

Question 1

An Ansible playbook includes a handler that restarts a service when a configuration file is changed. Which directive in a task triggers the handler?

Accepted Answer

notify:. The 'notify' directive is used to call a handler when a task makes a change (i.e., when the task's state is changed).

Answer

register:

Answer

when:

Answer

handlers:

Question 2

A bash script uses a loop to iterate over files in a directory. Which TWO of the following loop constructs will correctly iterate over each .txt file in the current directory? (Select TWO).

Accepted Answer

for file in *.txt; do. for file in *.txt expands to all matching filenames; the C-style for loop can also be used with array of filenames, but direct expansion is simpler.

Answer

for file in '*.txt'; do

Answer

for file in $(ls *.txt); do

Answer

for ((i=0; i<${#files[@]}; i++)); do

Question 3

A Linux administrator writes a bash script that needs to exit immediately if any command fails. Which of the following should be included at the beginning of the script?

Accepted Answer

set -e. The 'set -e' command causes the shell to exit if any command exits with a non-zero status, which is useful for error handling.

Answer

set -x

Answer

set -u

Answer

set -o pipefail

Question 4

An administrator needs to deploy an application stack that includes a web server and a database. The containers must be able to communicate with each other and be easily managed together. Which TWO tools or methods can accomplish this? (Select TWO.)

Accepted Answer

Docker Compose. Docker Compose allows defining multi-container applications in a single file and manages networking and dependencies. Kubernetes orchestrates containers across a cluster. Both can manage a stack of containers with networking.

Answer

Ansible playbook with docker_container module

Answer

Podman pods

Answer

Docker run with --link

Question 5

A Linux administrator wants to ensure a Bash script exits immediately if any command fails. Which directive should be included at the beginning of the script?

Accepted Answer

set -e. The set -e command tells the shell to exit if any command exits with a non-zero status.

Answer

set -o pipefail

Answer

set -u

Answer

set -x

Question 6

An administrator wants to capture network traffic on interface eth0, writing the output to a file for later analysis, without resolving hostnames. Which command accomplishes this?

Accepted Answer

tcpdump -i eth0 -w capture.pcap -n. tcpdump -i eth0 -w file.pcap -n captures packets without name resolution and writes to a file.

Answer

tcpdump -i eth0 -r capture.pcap

Answer

tcpdump -i any -w capture.pcap

Answer

tcpdump -n -w eth0 capture.pcap

Question 7

A Linux administrator needs to run a Docker container in detached mode with port mapping from host port 8080 to container port 80, and mount a host directory /data to /app/data inside the container. Which command achieves this?

Accepted Answer

docker run -d -p 8080:80 -v /data:/app/data --name webapp nginx. docker run -d -p 8080:80 -v /data:/app/data --name webapp nginx runs the container detached, maps ports, and mounts a bind volume.

Answer

docker run -it -p 8080:80 -v /data:/app/data --name webapp nginx

Answer

docker run -d -P -v /data:/app/data --name webapp nginx

Answer

docker start -d -p 8080:80 -v /data:/app/data webapp

Question 8

In a Bash script, what is the correct way to check if a file named '/etc/passwd' exists and is a regular file?

Accepted Answer

if [ -f /etc/passwd ]. The -f file test operator returns true if the file exists and is a regular file.

Answer

if [ -r /etc/passwd ]

Answer

if [ -e /etc/passwd ]

Answer

if [ -s /etc/passwd ]

Question 9

A DevOps engineer is creating a Dockerfile for a Node.js application. Which THREE of the following instructions are valid and commonly used in a Dockerfile? (Choose THREE.)

Accepted Answer

COPY . /app. Common Dockerfile instructions include FROM, RUN, COPY, EXPOSE, CMD, ENTRYPOINT, etc. The valid ones here are FROM, RUN, and COPY.

Answer

EXECUTE node app.js

Answer

INSTALL package.json

Question 10

An administrator wants to view the kernel ring buffer messages to check for hardware errors. Which command should be used?

Accepted Answer

dmesg. dmesg displays kernel ring buffer messages, often used for hardware diagnostics.

Answer

journalctl -k

Answer

iostat

Answer

vmstat

Question 11

An administrator is investigating a Bash script that is failing unexpectedly. They want to see each command as it is executed to debug the script. Which command should be added to the script?

Accepted Answer

set -x. set -x enables a trace of commands and their arguments as they are executed.

Answer

set -v

Answer

set -e

Answer

set -o xtrace

Question 12

A system administrator notices that a web server is running but users cannot connect to port 443. Which ss command will show if the server is listening on that port?

Accepted Answer

ss -tlnp. ss -tlnp shows listening TCP sockets with numeric ports and process info. -t for TCP, -l listening, -n numeric, -p process.

Answer

ss -s

Answer

ss -tuln

Answer

ss -tan

Question 13

In a Bash script, a variable is assigned the output of a command using: result=$(ls -l). What is the purpose of the $() syntax?

Accepted Answer

It runs the command and assigns its output to the variable. The $() syntax is command substitution, which captures the output of a command and stores it in a variable.

Answer

It expands the variable result

Answer

It checks if the command exists

Answer

It runs the command in a subshell and discards output

Question 14

A Linux administrator wants to run a container that stops automatically after the main process exits. Which Docker run flag should be used?

Accepted Answer

--rm. The --rm flag automatically removes the container when it exits, which is appropriate when the container should stop and be cleaned up after its main process finishes.

Answer

--stop-timeout

Answer

--restart=always

Answer

-d

Question 15

An administrator wants to test SMTP connectivity to a mail server without actually delivering an email. Which curl command is most appropriate?

Accepted Answer

curl -v smtp://mail.example.com:25. curl -v smtp://mail.example.com:25 connects to SMTP and shows handshake. -I sends HEAD, not SMTP. --resolve is for DNS override.

Answer

curl --resolve mail.example.com:25:10.0.0.1 smtp://mail.example.com

Answer

curl -o /dev/null smtp://mail.example.com

Answer

curl -I smtp://mail.example.com