102-500 Online Practice Questions

Explanation:
On a machine running several X servers, programs identify the different instances of the X11 server by a display name like :1. The display name consists of three parts: the hostname, the display number, and the screen number. The hostname is the name of the machine where the X server runs. The display number is a unique identifier that distinguishes different X server instances on the same machine. The screen number is used to address different physical screens that are managed by the same X server instance. The display name has the format hostname:displaynumber.screennumber. If the hostname is omitted, it means the local machine. The screen number is also optional and defaults to 0. For example, :1 means the second X server instance on the local machine, screen 0. remote:0.1 means the first X server instance on the remote machine, screen 1. The display name is part of the topic 106.1: Install and configure X11, which is one of the objectives of the LPI Linux Administrator - 102 exam12.
Reference: 1: LPI Linux Administrator - 102 (LPIC-1) 2: Exam 102 Objectives

Explanation:
The lowest numbered unprivileged TCP port is 1024. A port number is a 16-bit unsigned integer, thus ranging from 0 to 65535. The port numbers in the range from 0 to 1023 are the well-known ports or system ports. They are used by system processes that provide widely used types of network services. On Unix-like operating systems, a process must execute with superuser privileges to be able to bind a
network socket to an IP address using one of the well-known ports. Therefore, the lowest numbered port that can be used by a normal user without root access is 1024, which is the first unprivileged port123
Reference:
1: How to bind to port number less than 1024 with non root access?
2: lowest numbered unprivileged TCP port - Bing
3: List of TCP and UDP port numbers - Wikipedia
4: Privileged Ports - World Wide Web Consortium (W3C)
5: What is the lowest TCP port number? C TeachersCollegesj

Explanation:
The command nmtui is a curses application that provides easy access to the NetworkManager on the command line. It is included in the networkmanager package, along with nmcli, which is another command line interface for NetworkManager. nmtui allows the user to view, edit, activate and deactivate network connections, as well as set the system hostname. It has a simple and user-friendly interface that can be navigated with the keyboard or mouse12.
Reference: 1: Wireless Network Manager command line ncurses GUI. 2: NetworkManager - ArchWiki.

Explanation:
The /etc/nologin file is used to prevent all users except root from logging into the system. This file is usually created by the system administrator when the system is going down for maintenance or reboot. The file can contain a message that is displayed to the users who try to log in, explaining the reason for the system shutdown. The file is automatically removed by the system when it boots up again.
Reference: LPI 102-500 Exam Objectives, Topic 104: Administrative Tasks, 104.5 Manage user accounts
LPI 102-500 Study Guide, Chapter 4: User and Group Management, Section 4.3: Preventing Users from Logging In

Explanation:
The /etc/at.deny file specifies the user accounts that can NOT submit jobs via at or batch. The format of the file is a list of usernames, one on each line. Whitespace is not permitted. The superuser may always use at. If the file /etc/at.allow exists, only usernames mentioned in it are allowed to use at. If /etc/at.allow does not exist, /etc/at.deny is checked12. The at and batch commands use the files /usr/lib/cron/at.allow and /usr/lib/cron/at.deny to restrict usage on some systems3.
Reference: at.allow(5) - Linux man page
at.deny(5) [linux man page] - The UNIX and Linux Forums The at.allow and at.deny files - IBM