CompTIA XK0-005 Online Practice Questions and Exam Preparation

CompTIA XK0-005 Online Questions & Answers

• Question 121:

  A systems administrator created a user cron to run a scheduled database backup cronjob on the server at 1 a.m. every day. The following is the cronjob syntax:

  0 1 * * * /bin/sh backup.sh

  The backups, however, are not being created. When checking the crontab file, the administrator sees the following error:

  /var/spool/cron/crontab/cron: Permission denied Which of the following will permit the cronjob to execute?

  A. Creating the file cron.allow and adding user cron to it
  B. Giving cron ownership of the file /usr/bin/crontab
  C. Running sudo cron restart to activate the cronjob
  D. Running sudo crontab -u cron -e to edit the file with sudo
  A. Creating the file cron.allow and adding user cron to it

  ---

  Explanation

  The error indicates that the cron user does not have permission to run the cronjob. Creating a cron.allow file and adding the user cron to it will allow that user to run cronjobs. The cron.allow file is a security feature that controls which users are allowed to use cron.

• Question 122:

  Which of the following enables administrators to configure and enforce MFA on a Linux system?

  A. Kerberos
  B. SELinux
  C. PAM
  D. PKI
  C. PAM

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  Explanation

  The mechanism that enables administrators to configure and enforce MFA on a Linux system is PAM. PAM stands for Pluggable Authentication Modules, which is a framework for managing authentication and authorization on Linux systems. PAM allows the administrator to define the rules and policies for accessing various system resources and services, such as login, sudo, ssh, or cron. PAM also supports different types of authentication methods, such as passwords, tokens, biometrics, or smart cards. PAM can be used to implement MFA, which stands for Multi-Factor Authentication, which is a security technique that requires the user to provide more than one piece of evidence to prove their identity. MFA can enhance the security of the system and prevent unauthorized access. PAM enables administrators to configure and enforce MFA on a Linux system. This is the correct answer to the question. The other options are incorrect because they either do not manage authentication and authorization on Linux systems (Kerberos or PKI) or do not support MFA (SELinux).

  References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 17: Implementing Basic Security, page

  517.

• Question 123:

  A Linux engineer wants to give read-write-execute permissions for the cloud_users directory to user Oliver. Which of the following commands should the engineer use?

  A. setfacl -L Oliver /cloud_users
  B. setfacl -x rwx /cloud_users
  C. setfacl -P rwx /cloud_users
  D. setfacl -m u:Oliver /cloud_users
  D. setfacl -m u:Oliver /cloud_users

  ---

  Explanation

  The setfacl -m u:Oliver:rwx /cloud_users command modifies the ACL (Access Control List) for the directory cloud_users, granting the user Oliver read, write, and execute permissions. This is the correct syntax for assigning specific permissions to a user.

• Question 124:

  A systems administrator is tasked with preventing logins from accounts other than root, while the file /etc/nologin exists. Which of the following PAM modules will accomplish this task?

  A. pam_login.so
  B. pam_access.so
  C. pam_logindef.so
  D. pam_nologin.so
  D. pam_nologin.so

  ---

  Explanation

  The PAM module pam_nologin.so will prevent logins from accounts other than root, while the file /etc/nologin exists. This module checks for the existence of the file /etc/nologin and displays its contents to the user before denying access. The root user is exempt from this check and can still log in. This is the correct module to accomplish the task. The other options are incorrect because they are either non-existent modules (pam_login.so or pam_logindef.so) or do not perform the required function (pam_access.so controls access based on host, user, or time).

  References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 15: Managing Users and Groups, page 471.

• Question 125:

  A user is unable to remotely log on to a server using the server name server1 and port 22. The Linux engineer troubleshoots the issue and gathers the following information: Which of the following is most likely causing the issue?

  

  A. server 1 is not in the DNS.
  B. sshd is running on a non-standard port.
  C. sshd is not an active service.
  D. serverl is using an incorrect IP address.
  B. sshd is running on a non-standard port.

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  Explanation

  The sshd is the Secure Shell Daemon, which is a service that allows remote login to a Linux system using the SSH protocol. The output shows that the sshd is running on port 2222, which is a non-standard port for SSH. The default port for SSH is 22, which is what the user is trying to use. Therefore, the statement B is most likely causing the issue. The statements A, C, and D are incorrect because they do not explain why the user cannot log on using port 22.

  References: [How to Change SSH Port in Linux]

• Question 126:

  An administrator changed the default port of an SSH server to 2222 on myhost, and clients are not able to connect. The administrator runs some commands and receives the following output:

  vbnet

  Copy code

  $ ssh -p 2222 myhost

  ssh:connect to host myhost on port 2222: No route to host

  Which of the following commands should be run on myhost?

  A. firewall-cmd --zone=public --add-service=ssh
  B. firewall-cmd --zone=public --add-port=2222
  C. iptables --zone=public --add-service=ssh
  D. iptables --zone=public --add-port=2222
  B. firewall-cmd --zone=public --add-port=2222

  ---

  Explanation

  The administrator has likely updated the SSH server to listen on a non- standard port (2222), but the firewall rules were not updated to allow connections on this new port. The firewall-cmd command with the --add-port option allows traffic on a specific port through the firewall. The command should be executed on myhost to permit incoming SSH connections on port 2222.

  Red Hat Firewall Configuration

• Question 127:

  A Linux administrator needs to connect securely to a remote server in order to install application software. Which of the following commands would allow this connection?

  A. scp "ABC-key.pem" [email protected]
  B. sftp rooteiO.0.0.1
  C. telnet 10.0.0.1 80
  D. ssh -i "ABC-key.pem" [email protected]
  E. sftp "ABC-key.pem" [email protected]
  D. ssh -i "ABC-key.pem" [email protected]

  ---

  Explanation

  The command ssh -i "ABC-key.pem" [email protected] would allow the administrator to connect securely to the remote server in order to install application software. The ssh command is a tool for establishing secure and encrypted connections between remote systems. The -i option specifies the identity file that contains the private key for key-based authentication. The "ABC-key.pem" is the name of the identity file that contains the private key. The [email protected] is the username and the IP address of the remote server. The command ssh -i "ABC-key.pem" [email protected] will connect to the remote server using the private key and allow the administrator to install application software. This is the correct command to use to connect securely to the remote server. The other options are incorrect because they either do not use key-based authentication (sftp [email protected] or telnet 10.0.0.1 80) or do not use the correct syntax for the command (scp "ABCkey.pem" [email protected] instead of scp -i "ABC-key.pem" [email protected] or sftp "ABC-key.pem" [email protected] instead of sftp -i "ABC-key.pem" [email protected]).

  References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 17: Implementing Basic Security, page 513.

• Question 128:

  A Linux systems administrator is trying to execute a particular shell script on a server. The administrator reviews the following outputs: shell $ ./startup.sh bash: ./startup.sh: Permission denied $ ls -l startup.sh -rw-rw-r-- 1 companyabc companyabc 18 October 15:35 startup.sh Which of the following commands should the administrator use to allow the script to run?

  A. chown root startup.sh
  B. chmod 750 startup.sh
  C. chmod -x startup.sh
  D. chmod 400 startup.sh
  B. chmod 750 startup.sh

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  Explanation

  The script is missing the execute permission. Using chmod 750 startup.sh adds execute permissions for the owner and grants read and execute permissions for the group, allowing the script to run. Without execute permissions, the shell

  cannot run the script.

• Question 129:

  Which of the following is a benefit of a service mesh?

  A. Encrypted communication between two services in a Kubernetes environment
  B. Direct access to the Kubernetes API services through the use of tokens
  C. Elevated privileges in a Kubernetes pod to allow root access in a hardened cluster
  D. Creating PVCs in a Kubernetes cluster to store and manage persistent data
  A. Encrypted communication between two services in a Kubernetes environment

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  Explanation

  A service mesh provides secure, encrypted communication between microservices in a Kubernetes environment. It also provides features like traffic management, observability, and load balancing at the network layer. The most popular service mesh implementations, such as Istio, handle security by enforcing mutual TLS (mTLS) encryption between services, ensuring data privacy and integrity.

• Question 130:

  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
  A. useradd -d /comptia/projects user02

  ---

  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.