XK0-006 Practice Test 46 — 15 Questions

Question 1

A DevOps engineer needs to debug a bash script that unexpectedly fails when processing files. Which of the following should be added to the script to print each command before execution?

Accepted Answer

set -x. set -x enables a trace of each command, printing them to stderr before execution.

Answer

set -v

Answer

set -e

Answer

set -u

Question 2

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}. Parameter expansion ${myvar:0:5} extracts a substring starting at position 0 of length 5. The other options are incorrect syntax.

Answer

echo ${myvar#?????}

Answer

echo ${myvar:0-5}

Answer

echo ${myvar:5}

Question 3

A Bash script contains the following function:

```bash
myfunc() {
  local result="$(( $1 + $2 ))"
  echo "$result"
}
```

If the script calls `myfunc 5 10`, what is the output?

Accepted Answer

15. The function adds the two arguments (5+10=15) and echoes the result, which is 15.

Answer

510

Answer

5+10

Answer

the function returns nothing

Question 4

A Kubernetes YAML manifest defines a Deployment with 3 replicas. The administrator runs `kubectl get pods` and sees 3 running pods. They then run `kubectl scale deployment mydeployment --replicas=5`. What command would confirm the new number of replicas?

Accepted Answer

kubectl get deployment mydeployment. kubectl get deployment mydeployment shows the current replicas, desired replicas, and status.

Answer

kubectl get replicasets

Answer

kubectl get pods | wc -l

Answer

kubectl describe deployment mydeployment

Question 5

An administrator writes a bash script that uses a function to check if a file exists and is readable. The function returns 0 if the file meets the conditions, and 1 otherwise. Which of the following correctly implements this function?

Accepted Answer

check_file() { [[ -f "$1" ]] && [[ -r "$1" ]] && return 0; return 1; }. All four options are functionally correct. Option A chains two [[ ]] tests; Option B chains test commands with && and ||; Option C uses [ -a ]; Option D uses [[ && ]] inside an if statement. Each returns 0 only when the file exists and is readable, and returns 1 otherwise. If a single-answer question is required, the stem should be revised.

Question 6

A container is running a web server on port 8080 internally, and the administrator wants to access it on the host on port 80. Which Docker run option accomplishes this?

Accepted Answer

-p 80:8080. Port mapping is done using -p host_port:container_port. So -p 80:8080 maps host port 80 to container port 8080.

Answer

-P

Answer

-p 8080:80

Answer

--expose 8080

Question 7

An administrator needs to create a Docker network of type 'bridge' so that containers can communicate with each other by name. Which command creates a user-defined bridge network named 'my-net'?

Accepted Answer

docker network create -d bridge my-net. User-defined bridge networks provide automatic DNS resolution between containers. The command is 'docker network create' with the -d (driver) flag.

Answer

docker network create my-net

Answer

docker create network -d bridge my-net

Answer

docker network create --driver=overlay my-net

Question 8

A Kubernetes administrator needs to expose a deployment named 'webapp' as a service accessible externally on port 80. Which kubectl command should be used?

Accepted Answer

kubectl expose deployment webapp --type=NodePort --port=80. kubectl expose deployment webapp --type=NodePort --port=80 creates a service that exposes the deployment externally.

Answer

kubectl port-forward deployment/webapp 80:80

Answer

kubectl run webapp --port=80

Answer

kubectl create service clusterip webapp --port=80

Question 9

A Linux administrator needs to write a Bash script that runs a series of commands and stops immediately if any command fails. Which directive should be included at the beginning of the script?

Accepted Answer

set -e. The 'set -e' directive causes the script to exit immediately if any command returns a non-zero exit status, which is useful for error handling.

Answer

#!/bin/bash

Answer

trap ... ERR

Answer

set -x

Question 10

An administrator wants to use Ansible to ensure a service is running on a remote host. Which Ansible module should be used in a playbook?

Accepted Answer

service. The service module manages services on remote hosts. The command and shell modules run arbitrary commands but are not idempotent. The copy module copies files.

Answer

command

Answer

copy

Answer

shell

Question 11

A Kubernetes administrator needs to expose a deployment named 'web-app' running on port 80 internally within the cluster. Which kubectl command creates a service of type ClusterIP that maps port 80 to the target port 8080 on the pods?

Accepted Answer

kubectl expose deployment web-app --port=80 --target-port=8080. To create a ClusterIP service, use 'kubectl expose deployment web-app --port=80 --target-port=8080'. The --type=ClusterIP is default.

Answer

kubectl create service nodeport web-app --tcp=80:8080

Answer

kubectl expose pod web-app --port=80 --target-port=8080

Answer

kubectl create service clusterip web-app --tcp=80:8080

Question 12

A developer wants to view the logs from a running Docker container named 'myapp'. Which docker command should be used?

Accepted Answer

docker logs myapp. The 'docker logs' command fetches the logs of a container.

Answer

docker ps myapp

Answer

docker exec myapp logs

Answer

docker inspect myapp

Question 13

A Linux administrator needs to check which services are listening on TCP port 22. Which command should be used?

Accepted Answer

ss -tlnp | grep :22. The 'ss -tlnp' command shows listening TCP sockets with process information, making it suitable for checking services on port 22.

Answer

ping -p 22 localhost

Answer

ip addr show port 22

Answer

traceroute -p 22 localhost

Question 14

During boot, a Linux system displays a kernel panic. The administrator suspects a corrupt initramfs. Which GRUB boot parameter can be added to boot into an emergency shell before the initramfs is loaded, allowing repair?

Accepted Answer

rd.break. The rd.break parameter stops the boot process before the initramfs is fully loaded, dropping to a shell for troubleshooting.

Answer

single

Answer

init=/bin/bash

Answer

emergency

Question 15

A system administrator notices that a service named 'myapp' fails to start on a Linux server. The command 'systemctl status myapp' shows 'Active: failed (Result: exit-code)'. Which of the following is the BEST first step to diagnose the issue?

Accepted Answer

Run 'journalctl -u myapp.service' to inspect the service logs.. The 'journalctl -u myapp.service' command retrieves the systemd journal logs specifically for the myapp service, which contain the service's stdout, stderr, and any error messages generated during its failed startup attempt. Since the service failed with an exit code, these logs are the most direct source of diagnostic information to identify why the process terminated abnormally.

Answer

Run 'dmesg' to view kernel messages.

Answer

Run 'ps aux | grep myapp' to check if the process is running.

Answer

Edit the service file with 'systemctl edit myapp' and increase timeout values.