CompTIA CompTIA Certifications XK0-005 Questions & Answers

• Question 251:

  Users have been unable to reach www.comptia.org from a Linux server. A systems administrator is troubleshooting the issue and does the following:

  

  Based on the information above, which of the following is causing the issue?

  A. The name www.comptia.org does not point to a valid IP address.

  B. The server 192.168.168.53 is unreachable.

  C. No default route is set on the server.

  D. The network interface eth0 is disconnected.

  Correct Answer: B

  Explanation: The issue is caused by the server 192.168.168.53 being unreachable. This server is the DNS server configured in the /etc/resolv.conf file, which is used to resolve domain names to IP addresses. The ping command shows that

  the server cannot be reached, and the nslookup command shows that the name www.comptia.org cannot be resolved using this server. The other options are incorrect because:

  The name www.comptia.org does point to a valid IP address, as shown by the nslookup command using another DNS server (8.8.8.8). The default route is set on the server, as shown by the ip route command, which shows a default gateway

  of 192.168.168.1.

  The network interface eth0 is connected, as shown by the ip link command, which shows a state of UP for eth0. References: CompTIA Linux+ Study Guide, Fourth Edition, page 457-458, 461-462.

• Question 252:

  A Linux administrator would like to use systemd to schedule a job to run every two hours. The administrator creates timer and service definitions and restarts the server to load these new configurations. After the restart, the administrator checks the log file and notices that the job is only running daily. Which of the following is MOST likely causing the issue?

  A. The checkdiskspace.service is not running.

  B. The checkdiskspace.service needs to be enabled.

  C. The OnCalendar schedule is incorrect in the timer definition.

  D. The system-daemon services need to be reloaded.

  Correct Answer: C

  Explanation: The OnCalendar schedule is incorrect in the timer definition, which is causing the issue. The OnCalendar schedule defines when the timer should trigger the service. The format of the schedule is OnCalendar=- ::. If any of the fields are omitted, they are assumed to be *, which means any value. Therefore, the schedule OnCalendar=*-*-* 00:00:00 means every day at midnight, which is why the job is running daily. To make the job run every two hours, the schedule should be OnCalendar=*-*-* *:00:00/2, which means every hour divisible by 2 at the start of the minute. The other options are incorrect because they are not related to the schedule. The checkdiskspace.service is running, as shown by the output of systemct1 status checkdiskspace.service. The checkdiskspace.service is enabled, as shown by the output of systemct1 is-enabled checkdiskspace.service. The system-daemon services do not need to be reloaded, as the timer and service definitions are already loaded by the restart. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 14: Managing Processes and Scheduling Tasks, page 437.

• Question 253:

  An administrator attempts to rename a file on a server but receives the following error.

  

  The administrator then runs a few commands and obtains the following output:

  

  Which of the following commands should the administrator run NEXT to allow the file to be renamed by any user?

  A. chgrp reet files

  B. chacl -R 644 files

  C. chown users files

  D. chmod -t files

  Correct Answer: D

  Explanation: The command that the administrator should run NEXT to allow the file to be renamed by any user is chmod -t files. This command uses the chmod tool, which is used to change file permissions and access modes. The -t option removes (or sets) the sticky bit on a directory, which restricts deletion or renaming of files within that directory to only their owners or root. In this case, since files is a directory with sticky bit set (indicated by t in drwxrwxrwt), removing it will allow any user to rename or delete files within that directory. The other options are not correct commands for allowing any user to rename files within files directory. The chgrp reet files command will change the group ownership of files directory to reet, but it will not affect its permissions or access modes. The chacl -R 644 files command is invalid, as chacl is used to change file access control lists (ACLs), not permissions or access modes. The chown users files command will change the user ownership of files directory to users, but it will not affect its permissions or access modes. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 8: Managing Users and Groups; chmod(1) - Linux manual page

• Question 254:

  A Linux engineer needs to create a custom script, cleanup.sh, to run at boot as part of the system services. Which of the following processes would accomplish this task?

  A. Create a unit file in the /etc/default/ directory. systemct1 enable cleanup systemct1 is-enabled cleanup

  B. Create a unit file in the /etc/ske1/ directory. systemct1 enable cleanup systemct1 is-enabled cleanup

  C. Create a unit file in the /etc/systemd/system/ directory. systemct1 enable cleanup systemct1 is-enabled cleanup

  D. Create a unit file in the /etc/sysctl.d/ directory. systemct1 enable cleanup systemct1 is-enabled cleanup

  Correct Answer: C

  Explanation: The process that will accomplish the task of creating a custom script to run at boot as part of the system services is:

  Create a unit file in the /etc/systemd/system/ directory. A unit file is a configuration file that defines the properties and behavior of a systemd service. The systemd is a system and service manager that controls the startup and operation of

  Linux systems. The /etc/systemd/system/ directory is the location where the administrator can create and store custom unit files. The unit file should have a name that matches the name of the script, such as cleanup.service, and should

  contain the following sections and options:

  Run the command systemct1 enable cleanup. This command will enable the service and create the necessary symbolic links to start the service at boot. Run the command systemct1 is-enabled cleanup. This command will check the status of

  the service and confirm that it is enabled. This process will create a custom script, cleanup.sh, to run at boot as part of the system services. This is the correct process to use to accomplish the task. The other options are incorrect because

  they either use the wrong directory for the unit file (/etc/default/, /etc/skel/, or /etc/sysctl.d/) or do not create a unit file at all. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 15:

  Managing System Services, pages 457-459.

• Question 255:

  A systems administrator created a new Docker image called test. After building the image, the administrator forgot to version the release. Which of the following will allow the administrator to assign the v1 version to the image?

  A. docker image save test test:v1

  B. docker image build test:vl

  C. docker image tag test test:vl

  D. docker image version test:v1

  Correct Answer: C

  Explanation: The docker image tag test test:v1 command can be used to assign the v1 version to the image called test. This command creates a new tag for the existing image, without changing the original image. The docker image save test test:v1 command would save the image to a file, not assign a version. The docker image build test:vl command is invalid, as vl is not a valid version number. The docker image version test:v1 command does not exist. References: [CompTIA Linux+ (XK0-005) Certification Study Guide], Chapter 16: Virtualization and Cloud Technologies, page 500.

• Question 256:

  A server is experiencing intermittent connection issues. Some connections to the Internet work as intended, but some fail as if there is no connectivity. The systems administrator inspects the server configuration: Which of the following is MOST likely the cause of the issue?

  

  A. An internal-only DNS server is configured.

  B. The IP netmask is wrong for ens3.

  C. Two default routes are configured.

  D. The ARP table contains incorrect entries.

  Correct Answer: C

  Explanation: The most likely cause of the issue is that two default routes are configured on the server. The default route is the route that is used when no other route matches the destination of a packet. The default route is usually the gateway that connects the local network to the Internet. The server configuration shows that there are two default routes in the routing table, one with the gateway 192.168.1.1 and the other with the gateway 10.0.0.1. This can cause a conflict and confusion for the server when deciding which gateway to use for the outgoing packets. Some packets may be sent to the wrong gateway and fail to reach the Internet, while some packets may be sent to the correct gateway and work as intended. This can result in intermittent connection issues and inconsistent behavior. The administrator should remove one of the default routes and keep only the correct one for the network. This can be done by using the ip route del command or by editing the network configuration files. This will resolve the issue and restore the connectivity. The other options are incorrect because they are not supported by the outputs. The DNS server, the IP netmask, and the ARP table are not the causes of the issue. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 12: Managing Network Connections, pages 381-382.

• Question 257:

  Which of the following should be used to verify the integrity of a file?

  A. sha256sum

  B. fsck

  C. gpg --d

  D. hashcat

  Correct Answer: A

  The best tool to use to verify the integrity of a file is A. sha256sum. This tool will compute and display the SHA-256 hash of a file, which is a 64-digit hexadecimal number that uniquely identifies the file's content. By comparing the hash of a downloaded file with the hash provided by the file owner or source, you can confirm that the file has not been altered or corrupted during the transfer. The other tools are either not relevant or not suitable for this task. For example:

  B. fsck is a tool for checking and repairing the file system, but it does not verify the integrity of individual files.

  C. gpg -d is a tool for decrypting files that have been encrypted with GnuPG, but it does not verify the integrity of unencrypted files. D. hashcat is a tool for cracking passwords or hashes, but it does not verify the integrity of files.

• Question 258:

  A junior administrator updated the PostgreSQL service unit file per the data-base administrator's recommendation. The service has been restarted, but changes have not been applied. Which of the following should the administrator run for the changes to take effect?

  A. Systemct1 get--default

  B. systemct1 daemon--reload

  C. systemct1 enable postgresq1

  D. systemct1 mask postgresq1

  Correct Answer: B

  To apply changes to a systemd service unit file, the administrator needs to reload the systemd daemon using the command systemct1 daemon-reload (B). This will make systemd aware of the new or changed unit files. The other commands

  will not reload the systemd daemon or apply the changes. References:

  [CompTIA Linux+ Study Guide], Chapter 7: Managing System Services, Section:

  Modifying Systemd Services

  [How to Reload Systemd Services]

• Question 259:

  A Linux administrator created a new file system. Which of the following files must be updated to ensure the filesystem mounts at boot time?

  A. /etc/sysctl

  B. /etc/filesystems

  C. /etc/fstab

  D. /etc/nfsmount.conf

  Correct Answer: C

  Explanation: The file that must be updated to ensure the filesystem mounts at boot time is /etc/fstab. This file contains information about the filesystems that are mounted automatically by the mount -a command, which is usually invoked during the system startup. The /etc/fstab file has six fields for each filesystem: device name, mount point, filesystem type, mount options, dump frequency, and pass number. To add a new filesystem to the /etc/fstab file, you need to specify these fields correctly and make sure the mount point directory exists. The other options are not correct files for controlling persistent mount points of filesystems. The /etc/sysctl file is used to configure kernel parameters at runtime. The /etc/filesystems file is used to specify the order of filesystem types used by mount when no filesystem type is given. The /etc/nfsmount.conf file is used to set options for mounting NFS filesystems. References: Persistently mounting file systems; fstab(5) - Linux manual page

• Question 260:

  When trying to log in remotely to a server, a user receives the following message:

  

  The server administrator is investigating the issue on the server and receives the following outputs:

  

  Which of the following is causing the issue?

  A. The wrong permissions are on the user's home directory.

  B. The account was locked out due to three failed logins.

  C. The user entered the wrong password.

  D. The user has the wrong shell assigned to the account.

  Correct Answer: D

  Explanation: The user has the wrong shell assigned to the account, which is causing the issue. The output 1 shows that the user's shell is set to /bin/false, which is not a valid shell and will prevent the user from logging in. The output 2 shows that the user's home directory has the correct permissions (drwxr-xr-x), and the output 3 shows that the user entered the correct password and was accepted by the SSH daemon, but the session was closed immediately due to the invalid shell. The other options are incorrect because they are not supported by the outputs. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 13: Managing Network Services, page 413.