CompTIA XK0-005 Online Practice Questions and Exam Preparation

CompTIA XK0-005 Online Questions & Answers

• Question 441:

  A diagnostic tool reports a "host seems down" event for a server with an IP address of 192.168.47.44. Which of the following commands should the administrator use to confirm the host down event?

  A. nmap 192.168.47.0/32
  B. netcat 192.168.47.44
  C. nmap 192.168.47.44 -Pn
  D. ping -c 1 192.168.47.44
  D. ping -c 1 192.168.47.44

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  Explanation

  The ping -c 1 192.168.47.44 command sends one ICMP echo request to the specified host to check its availability. If the host is down, there will be no response. This is the quickest way to confirm if a host is reachable. nmap -Pn can also be used to check a host status, but ping is faster and lighter.

• Question 442:

  The security team has identified a web service that is running with elevated privileges A Linux administrator is working to change the systemd service file to meet security compliance standards. Given the following output:

  

  Which of the following remediation steps will prevent the web service from running as a privileged user?

  A. Removing the ExecStarWusr/sbin/webserver -D SOPTIONS from the service file
  B. Updating the Environment File line in the [Service] section to/home/webservice/config
  C. Adding the User-webservice to the [Service] section of the service file
  D. Changing the:nulti-user.target in the [Install] section to basic.target
  C. Adding the User-webservice to the [Service] section of the service file

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  Explanation

  The remediation step that will prevent the web service from running as a privileged user is adding the User=webservice to the [Service] section of the service file. The service 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 service file contains various sections and options that specify how the service should be started, stopped, and managed. The [Service] section defines how the service should be executed and what commands should be run. The User option specifies the user name or ID that the service should run as. The webservice is the name of the user that the administrator wants to run the web service as. The administrator should add the User=webservice to the [Service] section of the service file, which will prevent the web service from running as a privileged user, such as root, and improve the security of the system. This is the correct remediation step to use to prevent the web service from running as a privileged user. The other options are incorrect because they either do not change the user that the service runs as (removing the ExecStart=/usr/sbin/webserver -D OPTIONS from the service file or updating the EnvironmentFile line in the [Service] section to /home/webservice/config) or do not affect the user that the service runs as (changing the multi-user.target in the [Install] section to basic.target).

  References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 15: Managing System Services, page 458.

• Question 443:

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

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  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 444:

  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
  C. /etc/fstab

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  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 445:

  A Linux administrator would like to measure possible packet loss between a workstation and a remote web application that is running on port 443. Which of the following would be the best command for the administrator to use to display this information?

  A. ping -c 50
  B. tcpdump -p 443
  C. mtr -T -P 443
  D. traceroute -p 443
  C. mtr -T -P 443

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  Explanation

  mtr (My Traceroute) is a network diagnostic tool that combines the functionality of traceroute and ping. It shows real-time packet loss and latency on a hop-by-hop basis. The -T option uses TCP instead of ICMP, and the -P 443 option specifies the remote port. This provides the best method for checking packet loss on port 443.

• Question 446:

  A Linux systems administrator is resolving a privileged access issue for users who are members of an admin group.

  Which of the following configuration files should the administrator update so the users in the admin group will have root privileged access to the Linux system?

  A. /etc/sudoers
  B. /etc/login.defs
  C. /etc/group
  D. /etc/shadow
  A. /etc/sudoers

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  Explanation

  The /etc/sudoers file defines user privileges and access to root-level commands.

  Option A (Correct): The administrator should grant sudo privileges by modifying /etc/sudoers using visudo.

  Option B: /etc/login.defs controls system-wide authentication policies, not sudo access.

  Option C: /etc/group manages group memberships but does not grant sudo access.

  Option D: /etc/shadow stores password hashes, unrelated to sudo access.

• Question 447:

  When trying to connect from the bastion host to the remote server, a Linux user always forgets to add some required options in the SSH command line. Which of the following is the best way to permanently solve the user's issue?

  A. Write a connection script and put it in the user's home directory.
  B. Instruct the user to add the required options to the ~/.ssh/config file
  C. Add the required options to /etc/ssh/sshconfig
  D. Establish an alias for the SSH command with all the required options.
  B. Instruct the user to add the required options to the ~/.ssh/config file

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  Explanation

• Question 448:

  A systems administrator is trying to track down a rogue process that has a TCP listener on a network interface for remote command-and-control instructions.

  Which of the following commands should the systems administrator use to generate a list of rogue process names? (Select two).

  A. netstat -antp | grep LISTEN
  B. lsof -iTCP | grep LISTEN
  C. lsof -i:22 | grep TCP
  D. netstat -a | grep TCP
  E. nmap -p1-65535 | grep -i tcp
  F. nmap -sS 0.0.0.0/0
  A. netstat -antp | grep LISTEN
  B. lsof -iTCP | grep LISTEN

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  Explanation

  The best commands to use to generate a list of rogue process names that have a TCP listener on a network interface are A. netstat -antp | grep LISTEN and

  B. lsof -iTCP | grep LISTEN. These commands will show the process ID (PID) and name of the processes that are listening on TCP ports, which can be used to identify any suspicious or unauthorized processes. The other commands are either not specific enough, not valid, or not relevant for this task. For example:

  C. lsof -i:22 | grep TCP will only show the processes that are listening on port 22, which is typically used for SSH, and not any other ports.

  D. netstat -a | grep TCP will show all the TCP connections, both active and listening, but not the process names or IDs.

  E. nmap -p1-65535 | grep -i tcp will scan all the TCP ports on the local host, but not show the process names or IDs.

  F. nmap -sS 0.0.0.0/0 will perform a stealth scan on the entire internet, which is not only impractical, but also illegal in some countries.

• Question 449:

  A systems administrator creates a public key for authentication. Which of the following tools is most suitable to use when uploading the key to the remote servers?

  A. scp
  B. ssh-copy-id
  C. ssh-agent
  D. ssh-keyscan
  B. ssh-copy-id

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  Explanation

  The best tool to use when uploading the public key to the remote servers is

  B. ssh-copy-id. This tool will copy the public key from the local computer to the remote server and append it to the authorized_keys file, which is used for public key authentication. This tool will also create the necessary directories and files on the remote server if they do not exist. The other tools are either not suitable or not relevant for this task. For example:

  A. scp is a tool for securely copying files between hosts, but it does not automatically add the public key to the authorized_keys file.

  C. ssh-agent is a tool for managing private keys and passphrases, but it does not upload the public key to the remote server.

  D. ssh-keyscan is a tool for collecting public keys from remote hosts, but it does not upload the public key to the remote server.

• Question 450:

  A Linux administrator has logged in to a server for the first time and needs to know which services are allowed through the firewall. Which of the following options will return the results for which the administrator is looking?

  A. firewall-cmd --get-services
  B. firewall-cmd --check-config
  C. firewall-cmd --list-services
  D. systemct1 status firewalld
  C. firewall-cmd --list-services

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  Explanation

  The firewall-cmd --list-services command will return the results for which the administrator is looking. This command will list all services that are allowed through the firewall in the default zone or a specified zone. A service is a predefined set of ports and protocols that can be enabled or disabled by firewalld. The firewall-cmd --get-services command will list all available services that are supported by firewalld, not only those that are allowed through the firewall. The firewall-cmd -check-config command will check if firewalld configuration files are valid, not list services. The systemct1 status firewalld command will display information about the firewalld service unit, such as its state, PID, memory usage, and logs, not list services.

  References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 18: Securing Linux Systems, page 543.