CompTIA CompTIA Certifications XK0-005 Questions & Answers

• Question 271:

  A Linux administrator created the directory /project/access2all. By creating this directory, the administrator is trying to avoid the deletion or modification of files from non-owners. Which of the following will accomplish this goal?

  A. chmod +t /project/access2all

  B. chmod +rws /project/access2all

  C. chmod 2770 /project/access2all

  D. chmod ugo+rwx /project/access2all

  Correct Answer: A

  Explanation: The command that will accomplish the goal of avoiding the deletion or modification of files from non-owners is chmod +t /project/access2all. This command will set the sticky bit on the directory /project/access2all, which is a special permission that restricts file deletion or renaming to only the file owner, directory owner, or root user. This way, even if multiple users have write permission to the directory, they cannot delete or modify each other's files. The other options are not correct commands for accomplishing the goal. The chmod +rws /project/access2all command will set both the SUID and SGID bits on the directory, which are special permissions that allow a program or a directory to run or be accessed with the permissions of its owner or group, respectively. However, this does not prevent file deletion or modification from non-owners. The chmod 2770 /project/access2all command will set only the SGID bit on the directory, which means that any new files or subdirectories created in it will inherit its group ownership. However, this does not prevent file deletion or modification from non-owners. The chmod ugo+rwx /project/access2all command will grant read, write, and execute permissions to all users (user, group, and others) on the directory, which means that anyone can delete or modify any file in it. References: chmod(1) - Linux manual page; How to Use SUID, SGID, and Sticky Bits on Linux

• Question 272:

  A junior Linux administrator is tasked with installing an application. The installation guide states the application should only be installed in a run level 5 environment.

  

  Which of the following commands would ensure the server is set to runlevel 5?

  A. systemct1 isolate multi-user.target

  B. systemct1 isolate graphical.target

  C. systemct1 isolate network.target

  D. systemct1 isolate basic.target

  Correct Answer: B

  Explanation: The command that would ensure the server is set to runlevel 5 is systemct1 isolate graphical.target. This command will change the current target (or runlevel) of systemd to graphical.target, which is equivalent to runlevel 5 in SysV init systems. Graphical.target means that the system will start with a graphical user interface (GUI) and all services required for it. The other options are not correct commands for setting the server to runlevel 5. The systemct1 isolate multi-user.target command will change the current target to multi- user.target, which is equivalent to runlevel 3 in SysV init systems. Multiuser.target means that the system will start with multiple user logins and networking, but without a GUI. The systemct1 isolate network.target command will change the current target to network.target, which is not a real runlevel but a synchronization point for network-related services. Network.target means that network functionality should be available, but does not specify whether it should be started before or after it. The systemct1 isolate basic.target command will change the current target to basic.target, which is also not a real runlevel but a synchronization point for basic system services. Basic.target means that all essential services should be started, but does not specify whether it should be started before or after it. References: systemd System and Service Manager; systemd.special(7) - Linux manual page

• Question 273:

  A Linux administrator generated a list of users who have root-level command-line access to the Linux server to meet an audit requirement. The administrator analyzes the following /etc/passwd and /etc/sudoers files: $ cat /etc/passwd root:x: 0:0: :/home/root: /bin/bash lee: x: 500: 500: :/home/lee:/bin/tcsh mallory:x: 501:501: :/root:/bin/bash eve:x: 502: 502: /home/eve:/bin/nologin carl:x:0:503: :/home/carl:/bin/sh bob:x: 504: 504: : /home/bob:/bin/ksh alice:x: 505:505: :/home/alice:/bin/rsh $ cat /etc/sudoers Cmnd_Alias SHELLS = /bin/tcsh, /bin/sh, /bin/bash Cmnd_Alias SYSADMIN = /usr/sbin/tcpdump ALL = (ALL) ALL ALL = NOPASSWD: SYSADMIN Which of the following users, in addition to the root user, should be listed in the audit report as having root-level command-line access? (Select two).

  A. Carl

  B. Lee

  C. Mallory

  D. Eve

  E. Bob

  F. Alice

  Correct Answer: AC

  The users who have root-level command-line access are those who have either the same user ID (UID) as root, which is 0, or the ability to run commands as root using sudo. Based on the /etc/passwd and /etc/sudoers files, the users who meet these criteria are: Carl: Carl has the same UID as root, which is 0, as shown in the /etc/passwd file. This means that Carl can log in as root and execute any command with root privileges1 Mallory: Mallory has the ability to run commands as root using sudo, as shown in the /etc/sudoers file. The line ALL = (ALL) ALL means that any user can run any command as any other user, including root, by using sudo. Mallory can also use the root shell /bin/bash as her login shell, as shown in the /etc/passwd file2 Therefore, the correct answer is A and C. Lee, Eve, Bob, and Alice do not have root-level command-line access because they have different UIDs from root and they cannot use sudo to run commands as root. Lee can only use sudo to run the commands listed in the Cmnd_Alias SHELLS, which are /bin/tcsh, /bin/sh, and /bin/bash. Eve cannot log in at all because her login shell is /bin/nologin. Bob and Alice can only use sudo to run the command /usr/sbin/tcpdump without a password, as specified by the Cmnd_Alias SYSADMIN and the line ALL = NOPASSWD: SYSADMIN2

• Question 274:

  A Linux administrator is troubleshooting the root cause of a high CPU load and average.

  

  Which of the following commands will permanently resolve the issue?

  A. renice -n -20 6295

  B. pstree -p 6295

  C. iostat -cy 1 5

  D. kill -9 6295

  Correct Answer: D

  Explanation: The command that will permanently resolve the issue of high CPU load and average is kill -9 6295. This command will send a SIGKILL signal to the process with the PID 6295, which is the process that is consuming 99.7% of the CPU according to the top output. The SIGKILL signal will terminate the process immediately and free up the CPU resources. The kill command is used to send signals to processes by PID or name. The other options are not correct commands for resolving this issue. The renice -n -20 6295 command will change the priority (niceness) of the process with PID 6295 to -20, which is the highest priority possible. This will make the process more CPU-intensive, not less. The renice command is used to change the priority of running processes. The pstree - p 6295 command will show a tree of processes with PID 6295 as the root. This will not affect the CPU load or average, but only display information. The pstree command is used to display a tree of processes. The iostat -cy 1 5 command will show CPU and disk I/O statistics for 5 iterations with an interval of 1 second. This will also not affect the CPU load or average, but only display information. The iostat command is used to report CPU and I/O statistics. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter

  11: Troubleshooting Linux Systems; kill(1) - Linux manual page; renice(1) - Linux manual page; pstree(1) - Linux manual page; iostat(1) - Linux manual page

• Question 275:

  A Linux user reported the following error after trying to connect to the system remotely:

  ssh: connect to host 10.0.1.10 port 22: Resource temporarily unavailable

  The Linux systems administrator executed the following commands in the Linux system while trying to diagnose this issue:

  

  Which of the following commands will resolve this issue?

  A. firewall-cmd --zone=public --permanent --add-service=22

  B. systemct1 enable firewalld; systemct1 restart firewalld

  C. firewall-cmd --zone=public --permanent --add-service=ssh

  D. firewall-cmd --zone=public --permanent --add-port=22/udp

  Correct Answer: C

  Explanation: The firewall-cmd --zone=public --permanent --add-service=ssh command will resolve the issue by allowing SSH connections on port 22 in the public zone of the firewalld service. This command will add the ssh service to the permanent configuration of the public zone, which means it will persist after a reboot or a reload of the firewalld service. The firewall-cmd --zone=public --permanent --add-service=22 command is invalid, as 22 is not a valid service name. The systemct1 enable firewalld; systemct1 restart firewalld command will enable and restart the firewalld service, but it will not change the firewall rules. The firewall-cmd --zone=public --permanent --add-port=22/udp command will allow UDP traffic on port 22 in the public zone, but SSH uses TCP, not UDP. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 18: Securing Linux Systems, page 543.

• Question 276:

  Based on an organization's new cybersecurity policies, an administrator has been instructed to ensure that, by default, all new users and groups that are created fall within the specified values below.

  

  To which of the following configuration files will the required changes need to be made?

  A. /etc/login.defs

  B. /etc/security/limits.conf

  C. /etc/default/useradd

  D. /etc/profile

  Correct Answer: A

  Explanation: The required changes need to be made to the /etc/login.defs configuration file. The /etc/login.defs file defines the default values for user and group IDs, passwords, shells, and other parameters for user and group creation. The file contains the directives UID_MIN, UID_MAX, GID_MIN, and GID_MAX, which set the minimum and maximum values for automatic user and group ID selection. The administrator can edit this file and change the values to match the organization's new cybersecurity policies. This is the correct file to modify to accomplish the task. The other options are incorrect because they either do not affect the user and group IDs (/etc/security/limits.conf or /etc/profile) or do not set the default values (/etc/default/useradd). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 15: Managing Users and Groups, page 463.

• Question 277:

  Which of the following data structures is written in JSON?

  

  A. Option A

  B. Option B

  C. Option C

  D. Option D

  Correct Answer: C

  Explanation: Option C is the only data structure that is written in JSON format. JSON stands for JavaScript Object Notation, and it is a lightweight and human-readable data interchange format. JSON uses curly braces to enclose objects, which consist of key-value pairs separated by commas. JSON uses square brackets to enclose arrays, which consist of values separated by commas. JSON supports six data types: strings, numbers, booleans, null, objects, and arrays. Option C follows these rules and syntax of JSON, while the other options do not. Option A is written in XML format, which uses tags to enclose elements and attributes. Option B is written in YAML format, which uses indentation and colons to define key-value pairs. Option D is written in INI format, which uses sections and equal signs to define key-value pairs. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 21: Automating Tasks with Ansible, page 591.

• Question 278:

  A systems administrator installed a new software program on a Linux server. When the systems administrator tries to run the program, the following message appears on the screen.

  

  Which of the following commands will allow the systems administrator to check whether the system supports virtualization?

  A. dmidecode -s system-version

  B. lscpu

  C. sysctl -a

  D. cat /sys/device/system/cpu/possible

  Correct Answer: B

  Explanation: The command that will allow the systems administrator to check whether the system supports virtualization is lscpu. This command will display information about the CPU architecture, such as the number of CPUs, cores, sockets, threads, model name, frequency, cache size, and flags. One of the flags is vmx (for Intel processors) or svm (for AMD processors), which indicates that the CPU supports hardware virtualization. If the flag is present, it means that the system supports virtualization. If the flag is absent, it means that the system does not support virtualization or that it is disabled in the BIOS settings. The other options are not correct commands for checking whether the system supports virtualization. The dmidecode -s system-version command will display the version of the system, such as the product name or serial number, but not the CPU information. The sysctl -a command will display all the kernel parameters, but not the CPU flags. The cat /sys/devices/system/cpu/possible command will display the range of possible CPUs that can be online or offline, but not the CPU features. References: lscpu(1) - Linux manual page; How To Check If Virtualization is Enabled in Windows 10 / 11

• Question 279:

  A developer reported an incident involving the application configuration file /etc/httpd/conf/httpd.conf that is missing from the server. Which of the following identifies the RPM package that installed the configuration file?

  A. rpm -qf /etc/httpd/conf/httpd.conf

  B. rpm -ql /etc/httpd/conf/httpd.conf

  C. rpm --query /etc/httpd/conf/httpd.conf

  D. rpm -q /etc/httpd/conf/httpd.conf

  Correct Answer: A

  Explanation: The rpm -qf /etc/httpd/conf/httpd.conf command will identify the RPM package that installed the configuration file. This command will query the database of installed packages and display the name of the package that owns the specified file. The rpm -ql /etc/httpd/conf/httpd.conf command is invalid, as -ql is not a valid option for rpm. The rpm --query /etc/httpd/conf/httpd.conf command is incorrect, as --query requires a package name, not a file name. The rpm -q /etc/ httpd/conf/httpd.conf command is incorrect, as -q requires a package name, not a file name. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 19: Managing Packages and Software, page 560.

• Question 280:

  A systems administrator is investigating why one of the servers has stopped connecting to the internet.

  

  Which of the following is causing the issue?

  A. The DNS address has been commented out in the configuration file.

  B. The search entry in the /etc/resolv.conf file is incorrect.

  C. Wired connection 1 is offline.

  D. No default route is defined.

  Correct Answer: D

  Explanation: The issue is caused by the lack of a default route defined in the /etc/sysconfig/network-scripts/ifcfg-enp0s3 file. A default route is a special route that specifies where to send packets that do not match any other routes in the routing table. Without a default route, the server will not be able to communicate with hosts outside its local network. The default route is usually configured with the GATEWAY option in the network interface configuration file. For example, to set the default gateway to 192.168.1.1, the file should contain: GATEWAY=192.168.1.1 The other options are not causing the issue. The DNS address is not commented out in the configuration file, it is specified with the DNS1 option. The search entry in the /etc/resolv.conf file is correct, it specifies the domain name to append to unqualified hostnames. Wired connection 1 is online, as indicated by the ONBOOT=yes option and the output of ip link show enp0s3 command. References: Configuring IP Networking with nmcli; Configuring IP Networking with ifcfg Files