CompTIA CompTIA Certifications XK0-005 Questions & Answers

• Question 231:

  A systems administrator is troubleshooting a connectivity issue pertaining to access to a system named db.example.com. The system IP address should be 192.168.20.88. The administrator issues the dig command and receives the following output:

  

  The administrator runs grep db.example.com /etc/hosts and receives the following output:

  

  Given this scenario, which of the following should the administrator do to address this issue?

  A. Modify the /etc/hosts file and change the db.example.com entry to 192.168.20.89.

  B. Modify the /etc/network file and change the db.example.com entry to 192.168.20.88.

  C. Modify the /etc/network file and change the db.example.com entry to 192.168.20.89.

  D. Modify the /etc/hosts file and change the db.example.com entry to 192.168.20.88.

  Correct Answer: D

  Explanation: The administrator should modify the /etc/hosts file and change the db.example.com entry to 192.168.20.88 to address the issue. The /etc/hosts file is a file that maps hostnames to IP addresses on Linux systems. The file can be used to override the DNS resolution and provide a local lookup for hostnames. The dig output shows that the DNS returns the IP address 192.168.20.88 for the hostname db.example.com, which is the correct IP address of the system. The grep output shows that the /etc/hosts file contains an entry for db.example.com with the IP address 192.168.20.89, which is the wrong IP address of the system. This can cause a conflict and prevent the system from being accessed by the hostname. The administrator should modify the /etc/hosts file and change the db.example.com entry to 192.168.20.88, which is the correct IP address of the system. This will align the /etc/hosts file with the DNS and allow the system to be accessed by the hostname. The administrator should modify the /etc/hosts file and change the db.example.com entry to 192.168.20.88 to address the issue. This is the correct answer to the question. The other options are incorrect because they either do not modify the /etc/hosts file (modify the /etc/network file and change the db.example.com entry to 192.168.20.88 or modify the /etc/network file and change the db.example.com entry to 192.168.20.89) or do not change the IP address to the correct one (modify the /etc/hosts file and change the db.example.com entry to 192.168.20.89). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 12: Managing Network Connections, page 378.

• Question 232:

  A Linux administrator needs to analyze a failing application that is running inside a container. Which of the following commands allows the Linux administrator to enter the running container and analyze the logs that are stored inside?

  A. docker run -ti app /bin/sh

  B. podman exec -ti app /bin/sh

  C. podman run -d app /bin/bash

  D. docker exec -d app /bin/bash

  Correct Answer: B

  Explanation: Podman exec -ti app /bin/sh allows the Linux administrator to enter the running container and analyze the logs that are stored inside. This command uses the podman tool, which is a daemonless container engine that can run and manage containers on Linux systems. The exec option executes a command inside an existing container, in this case app, which is the name of the container that runs the failing application. The -ti option allocates a pseudo-TTY and keeps STDIN open, allowing for interactive shell access to the container. The /bin/sh argument specifies the shell command to run inside the container, which can be used to view and manipulate the log files. The other options are not correct commands for entering a running container and analyzing the logs. Docker run -ti app /bin/sh creates a new container from the app image and runs the /bin/sh command inside it, but does not enter the existing container that runs the failing application. Podman run -d app /bin/bash also creates a new container from the app image and runs the /bin/bash command inside it, but does so in detached mode, meaning that it runs in the background without interactive shell access. Docker exec -d app /bin/bash executes the /bin/bash command inside the existing app container, but also does so in detached mode, without interactive shell access. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 18: Automating Tasks; View container logs | Docker Docs; How to see the logs of a docker container - Stack Overflow

• Question 233:

  A developer is trying to install an application remotely that requires a graphical interface for installation. The developer requested assistance to set up the necessary environment variables along with X11 forwarding in SSH. Which of the following environment variables must be set in remote shell in order to launch the graphical interface?

  A. $RHOST

  B. SETENV

  C. $SHELL

  D. $DISPLAY

  Correct Answer: D

  Explanation: The environment variable that must be set in remote shell in order to launch the graphical interface is $DISPLAY. This variable tells X11 applications where to display their windows on screen. It usually has the form hostname:displaynumber.screennumber, where hostname is the name of the computer running the X server, displaynumber is a unique identifier for an X display on that computer, and screennumber is an optional identifier for a screen within an X display. For example, localhost:0.0 means display number 0 on the local host. If the hostname is omitted, it defaults to the local host. The other options are not correct environment variables for launching the graphical interface. $RHOST is a variable that stores the name of the remote host, but it is not used by X11 applications. SETENV is a command that sets environment variables in some shells, but it is not an environment variable itself. $SHELL is a variable that stores the name of the current shell, but it is not related to X11 forwarding. References: How to enable or disable X11 forwarding in an SSH server; How to Configure X11 Forwarding Using SSH In Linux

• Question 234:

  A user is unable to log on to a Linux workstation. The systems administrator executes the following command:

  cat /etc/shadow | grep user1

  The command results in the following output:

  user1 :! $6$QERgAsdvojadv4asdvaarC/9dj34GdafGVaregmkdsfa:18875:0:99999:7 :::

  Which of the following should the systems administrator execute to fix the issue?

  A. chown -R userl:user1 /home/user1

  B. sed -i '/ ::: / :: /g' /etc/shadow

  C. chgrp user1:user1 /home/user1

  D. passwd -u user1

  Correct Answer: D

  The output shows that the user1 account has a locked password, indicated by the exclamation point (!) in the second field of the /etc/shadow file1. To unlock the password and allow the user to log in, the systems administrator should use the passwd command with the -u (unlock) option2. References: 1: Understanding the /etc/shadow File 2: How To Use The Passwd Command In Linux

• Question 235:

  A Linux systems administrator receives a notification that one of the server's filesystems is full. Which of the following commands would help the administrator to identify this filesystem?

  A. lsblk

  B. fdisk

  C. df -h

  D. du -ah

  Correct Answer: C

  Explanation: The df -h command can be used to identify the filesystem that is full. This command displays the disk usage of each mounted filesystem in a human-readable format, showing the total size, used space, available space, and percentage of each filesystem. The lsblk command displays information about block devices, not filesystems. The fdisk command can be used to manipulate partition tables, not check disk usage. The du -ah command displays the disk usage of each file and directory in a human-readable format, not the filesystems. References: [CompTIA Linux+ (XK0-005) Certification Study Guide], Chapter 14: Managing Disk Storage, page 454.

• Question 236:

  After connecting to a remote host via SSH, an administrator attempts to run an application but receives the following error:

  [user@workstation ~]$ ssh admin@srv1

  Last login: Tue Mar 29 18:03:34 2022

  [admin@srvl ~] $ /usr/local/bin/config_manager

  Error: cannot open display:

  [admin@srv1 ~] $

  Which of the following should the administrator do to resolve this error?

  A. Disconnect from the SSH session and reconnect using the ssh -x command.

  B. Add Options X11 to the /home/admin/.ssh/authorized_keys file.

  C. Open port 6000 on the workstation and restart the firewalld service.

  D. Enable X11 forwarding in /etc/ssh/ssh_config and restart the server.

  Correct Answer: A

  The error indicates that the application requires an X11 display, but the SSH session does not forward the X11 connection. To enable X11 forwarding, the administrator needs to use the ssh -X option, which requests X11 forwarding with

  authentication spoofing. This will set the DISPLAY environment variable on the remote host and allow the application to open a window on the local display.

  References

  CompTIA Linux+ (XK0-005) Certification Study Guide, page 314 Open a window on a remote X display (why "Cannot open display")?, answer by Gilles `SO- stop being evil'

• Question 237:

  A Linux administrator needs to create a new user named user02. However, user02 must be in a different home directory, which is under /comptia/projects. Which of the following commands will accomplish this task?

  A. useradd -d /comptia/projects user02

  B. useradd -m /comptia/projects user02

  C. useradd -b /comptia/projects user02

  D. useradd -s /comptia/projects user02

  Correct Answer: A

  Explanation: The command useradd -d /comptia/projects user02 will accomplish the task of creating a new user named user02 with a different home directory. The useradd command is a tool for creating new user accounts on Linux systems. The - d option specifies the home directory for the new user, which is the directory where the user's personal files and settings are stored. The /comptia/projects is the path of the home directory for the new user, which is different from the default location of /home/user02. The user02 is the name of the new user. The command useradd -d /comptia/projects user02 will create a new user named user02 with a home directory under /comptia/projects. This is the correct command to use to accomplish the task. The other options are incorrect because they either do not specify the home directory for the new user (useradd -m /comptia/projects user02 or useradd -s /comptia/projects user02) or do not use the correct option for the home directory (useradd -b /comptia/projects user02 instead of useradd -d /comptia/projects user02). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 13: Managing Users and Groups, page 403.

• Question 238:

  Ann, a security administrator, is performing home directory audits on a Linux server. Ann issues the su Joe command and then issues the Is command. The output displays files that reside in Ann's home directory instead of Joe's. Which of the following represents the command Ann should have issued in order to list Joe's files?

  A. su - Joe

  B. sudo Joe

  C. visudo Joe

  D. pkexec joe

  Correct Answer: A

  The su command is used to switch to another user account on Linux systems. The - option makes the shell a login shell, which means that it will read the profile and environment variables of the target user. Without this option, the shell will retain the environment variables of the original user. This can cause confusion when issuing commands that depend on these variables, such as ls, which uses the $HOME variable to determine the home directory. Therefore, Ann should have issued su - Joe to list Joe's files instead of her own. References: [How to Use su Command in Linux with Examples]

• Question 239:

  A user is attempting to log in to a Linux server that has Kerberos SSO ena-bled. Which of the following commands should the user run to authenticate and then show the ticket grants? (Select TWO).

  A. kinit

  B. klist

  C. kexec

  D. kioad

  E. pkexec

  F. realm

  Correct Answer: AB

  The following commands can help the user to authenticate and show the ticket grants using Kerberos SSO on a Linux server:

  kinit: This command obtains and caches an initial ticket-granting ticket (TGT) for the user from the Kerberos key distribution center (KDC). The user needs to enter their password or use a keytab file to authenticate1. klist: This command lists

  the cached tickets, including the TGT and any service tickets, for the user. It also shows the expiration time and flags for each ticket2. For example, the user can run the following commands to log in and view their tickets:

  $ kinit username@REALM

  Password for username@REALM:

  $ klist

  Ticket cache: FILE:/tmp/krb5cc_1000

  Default principal: username@REALM

  Valid starting Expires Service principal

  04/06/2023 16:06:59 04/07/2023 02:06:59 krbtgt/REALM@REALM renew until 04/13/2023 16:06:59

  References:

  kinit(1) - Linux man page, section "Description".

  klist(1) - Linux man page, section "Description".

• Question 240:

  A file called testfile has both uppercase and lowercase letters: $ cat testfile ABCDEfgH IJKLmnoPQ abcdefgH ijklLMNopq A Linux administrator is tasked with converting testfile into all uppercase and writing it to a new file with the name uppercase. Which of the following commands will achieve this task?

  A. tr '(A-Z}' '{a-z}' < testfile > uppercase

  B. echo testfile | tr "[Z-A]" "[z-a]" < testfile > uppercase

  C. cat testfile | tr '{z-a)' '{Z-A}' < testfile > uppercase

  D. tr '[a-z]' '[A-Z]' < testfile > uppercase

  Correct Answer: D

  This command will use the tr tool to translate all lowercase letters in the testfile to uppercase letters and write the output to the uppercase file. The first argument `[a-z]' specifies the set of characters to be replaced, and the second argument ` [A-Z]' specifies the set of characters to replace with. The `<' symbol redirects the input from the testfile, and the `>' symbol redirects the output to the uppercase file12. References: 1: Linux Tr Command - javatpoint 2: Linux tr Command with Examples - phoenixNAP