Free 102-500 practice test: 30 questions with answers

With a /24 mask the network is 192.168.10.0 and the broadcast address is the last address in that range, 192.168.10.255. 192.168.10.0 is the network address, 192.168.0.255 belongs to a different network, and 192.168.10.38 is just the next host address.

HTTPS uses TCP port 443 by default. Port 80 is the default for plain HTTP, port 25 is used for SMTP mail transfer, and port 53 is used for DNS.

TCP guarantees ordered, reliable delivery over a connection, and both TCP and UDP use port numbers to address services. UDP has no handshake, acknowledgements or retransmission, and TCP is connection-oriented, so the other statements are wrong.

netplan reads its YAML files from /etc/netplan and generates the configuration for the selected renderer. /etc/network/interfaces belongs to the ifupdown system used on Debian, /etc/sysconfig/network-scripts belongs to older Red Hat style systems, and /etc/resolv.conf holds DNS resolver settings rather than interface definitions.

ip route show prints the kernel routing table, including any default route through a gateway. ip link show lists the network interfaces, ip neigh show lists the neighbour (ARP) cache, and ip addr show lists the addresses assigned to interfaces.

usermod -aG appends the group to the supplementary list without removing existing memberships. Using -G alone replaces the whole list, groupmod has no option for adding members, and useradd cannot modify an account that already exists.

/etc/passwd holds the user account entries and /etc/group holds group definitions and their members. /etc/fstab lists the filesystems to mount and /etc/hostname stores the system's host name, so neither describes accounts.

The crontab fields are minute, hour, day of month, month and day of week, so 30 6 * * 1-5 runs at 06:30 from Monday to Friday. Swapping minute and hour gives an invalid hour, 0-6 in the weekday field means every day, and 1-5 in the day-of-month field restricts dates instead of weekdays.

The at command queues a single job to run at a specified time and then removes it. crontab -e edits recurring cron entries, anacron runs periodic jobs on machines that are not always powered on, and batch runs jobs when the system load drops rather than at a set time.

LC_TIME controls only the date and time format category, so it changes dates while LANG keeps the other categories. LC_ALL overrides every category including messages, LC_MESSAGES changes only program message text, and LANGUAGE selects translations of messages rather than date formats.

chronyd is a daemon that keeps the system clock synchronised with NTP servers. The cron daemon runs scheduled jobs, syslogd records log messages, and logrotate rotates log files, so none of them adjusts the clock.

journalctl -u filters the journal by unit name, so journalctl -u sshd shows only sshd's entries. logrotate forces log rotation, cat would print a configuration file rather than the journal, and ls -l only lists the journal directory.

emerg is the highest syslog priority and is reserved for a system that is unusable. alert means immediate action is needed while the system still works, crit marks critical conditions, and err marks ordinary errors.

/etc/aliases maps local mail recipients to other addresses, and newaliases rebuilds the alias database that the mail transfer agent reads. /etc/hosts maps host names to addresses, /etc/services lists port names, and /etc/resolv.conf configures DNS resolver settings, so none of them handles mail aliasing.

CUPS, the Common UNIX Printing System, serves its administration interface on port 631. SANE is the scanner framework, ALSA is the kernel sound architecture, and PulseAudio is a sound server, so none of them manages print queues.

-perm -4000 matches files in which the setuid bit is set, regardless of the other permission bits. -perm 0777 matches only files with exactly mode 777, -user root selects files by owner, and -name setuid matches only files whose name is setuid.

visudo locks /etc/sudoers, lets the administrator edit it and checks the syntax before saving, which prevents a broken file from disabling sudo. passwd changes passwords, chage manages password aging, and usermod changes account attributes, so none of them edits sudo rules.

last reads the login records in /var/log/wtmp and shows past sessions with the user, terminal and time. uptime reports how long the system has been running, history lists the current user's shell commands, and ps aux lists running processes.

Public-key encryption uses the recipient's public key, and only the matching private key held by the recipient can decrypt the file. The sender's private key is used for signing, the recipient's private key is held only by the recipient and is needed for decryption, and a shared passphrase gives symmetric encryption rather than public-key encryption.

PermitRootLogin no stops the root account from logging in through sshd, while other accounts keep working. PasswordAuthentication no would disable passwords for every account, Port 2222 only changes the listening port, and X11Forwarding yes enables graphical forwarding, so none of them restricts root.

Bash reads ~/.bashrc for interactive non-login shells such as a new terminal window, which is why aliases and prompt settings placed there appear in those windows. ~/.bash_logout runs when a login shell exits, ~/.bash_history only stores past commands, and ~/.inputrc configures readline key bindings rather than the shell startup.

The shebang selects the interpreter, so dash parses the file and rejects bash-only arrays and [[ ]] with syntax errors. Dash does not implement bash extensions, the kernel uses the shebang interpreter rather than substituting bash, and scripts are not run in the login shell.

The 'Permission denied' error means the execute bit is missing, and chmod u+x adds it for the owner. chown only changes ownership, recursive 777 on / is an unrelated and dangerous change, and editing PATH has no effect when the script is started with ./ .

Exporting a variable places it in the environment that child processes inherit, and each child receives a copy made when it starts. Unexported shell variables stay local to the shell, positional parameters exist only during the script invocation, and a child process cannot modify its parent's variables.

$(command) runs the command in a subshell and substitutes its output, and it nests without any escaping. ${command} is parameter expansion, $[command] is an obsolete arithmetic form, and %{command} is not valid shell syntax.

The X server is the display server that controls the screen and routes input events to client applications. The window manager arranges and decorates windows, the display manager presents the login screen, and the desktop environment is a bundle of panels and applications built on top of X.

Orca is the screen reader used with GNOME to speak interface elements and focus changes. The other options are X11 command-line tools: xrandr configures monitor resolution and layout, xinput manages input devices, and xmodmap changes the keyboard mapping, and none of them provides speech output.

The display manager, such as GDM, LightDM or SDDM, shows the graphical login prompt and starts the user's session. The X server provides the display, a window manager controls window placement, and a desktop environment supplies panels and applications after login.

DISPLAY names the X server and screen a client should draw on, such as localhost:10.0 when forwarding is used. TERM describes the terminal type, PATH lists command directories, and LANG selects the locale, so none of them selects the X display.

~/.xinitrc is read by startx and xinit and lists the programs to launch, such as the window manager. ~/.Xresources holds application resource settings, ~/.Xauthority stores X authorization cookies, and ~/.xsession-errors collects error output from the session.