EX200 practice questions and answers

Correct answer: A — /etc/skel

useradd populates a new home directory from /etc/skel, which is how default dotfiles are distributed. /etc/default holds tool defaults, the other paths are not used for this purpose.

Correct answer: A, B — top · ps aux --sort=-%cpu | head

top gives a live ordered view and the sorted ps output gives a snapshot, both ranked by CPU usage. df, lsblk, and blkid all report storage information.

Correct answer: A — sestatus

sestatus prints whether SELinux is enabled, the current and configured modes, and the loaded policy. setenforce changes the mode, restorecon fixes file contexts, and semanage login lists login mappings.

Correct answer: A — systemctl rescue

systemctl rescue switches the running system into rescue mode for the current session only. poweroff shuts the machine down, set-default makes the change permanent, and masking prevents the target from being used at all.

Correct answer: A — command >> file

The double angle bracket appends, while a single one truncates the file first. 2> redirects standard error, and the left angle bracket reads the file as standard input.

Correct answer: A — Set Storage=persistent in /etc/systemd/journald.conf and restart systemd-journald

Persistent storage writes the journal under /var/log/journal so previous boots remain queryable. Vacuuming deletes old entries, removing the journal directory reverts to volatile storage, and Storage=none disables journal storage entirely.

Correct answer: A — defaults, which includes auto

The defaults option set includes auto, so the filesystem is mounted during boot and by mount -a. noauto explicitly prevents that, user allows non-root mounting, and loop is for mounting an image file.

Correct answer: A — renice 10 -p 1234

renice changes the nice value of an existing process, and a higher value means lower priority. nice sets the value when starting a new command, kill sends a signal, and taskset manages CPU affinity.

Correct answer: A — stratis pool create mypool /dev/sdb

The stratis command manages pools and filesystems in the Stratis local storage management layer. vgcreate belongs to LVM, there is no mkfs.stratis, and Stratis is not a partition table label.

Correct answer: A — dnf history undo last

dnf keeps a transaction history and undo reverses the selected transaction. There is no remove --all in this sense, rebuilddb repairs the rpm database, and makecache refreshes repository metadata.

Correct answer: A, B — Add a forwarding rule such as *.* @@logserver:514 to the rsyslog configuration · Restart or reload the rsyslog service so the change takes effect

A forwarding action in the configuration plus a service reload is all that is needed on the client side. fstab describes filesystems, disabling the journal removes local logging, and relaxing SELinux is not a configuration step for log forwarding.

Correct answer: A — The files carry the wrong SELinux context; run restorecon -Rv /var/www/html

Moving a file preserves its original context, so restorecon relabels it to the type the web server is allowed to read. Running as root is unnecessary and unsafe, disabling SELinux removes a protection rather than fixing the label, and firewalls do not affect local file access.

Correct answer: A — setsebool -P httpd_can_network_connect on

The -P flag writes the boolean to policy so it survives a reboot. Without it the change is runtime only, setenforce disables enforcement entirely, and chcon relabels files rather than toggling a boolean.

Correct answer: A — $?

$? is the exit status of the last command, with zero meaning success. $! holds the last background PID, $# the argument count, and $0 the script name.

Correct answer: A, B — set -e · set -o pipefail

set -e exits on an unhandled non-zero status and pipefail makes a pipeline fail if any stage fails. set +e disables the behaviour, ignoring the ERR trap suppresses handling, and discarding standard error only hides messages.

Correct answer: A, B — pvs · lvs

pvs and lvs summarise physical and logical volumes respectively, with vgs covering volume groups. mkswap formats swap, fsck checks filesystems, and sync flushes buffers.

Correct answer: A — The setgid bit, applied with chmod g+s

setgid on a directory makes new entries take the directory's group, which is how shared project directories work. setuid on a directory has no such effect on Linux, the sticky bit restricts deletion to the owner, and the others execute bit only permits traversal.

Correct answer: A, B — ip route show default · ip addr show ens192

ip route show default prints the gateway and ip addr show reports the interface's addresses. getenforce, semanage, and restorecon are SELinux tools.

Correct answer: A — for f in /etc/myapp/*.conf; do ...; done

A for loop over a glob expands to each matching path in turn. if tests a command's exit status, case matches one value against patterns, and the while form shown is not valid syntax.

Correct answer: A — /etc/yum.repos.d/ with .repo files

dnf reads .repo files from /etc/yum.repos.d, which is retained from yum for compatibility. The apt path belongs to Debian systems, the cache directory holds downloaded metadata, and rpm macros configure build and query behaviour.

Correct answer: A — 0027

Files are created from base 666 minus the umask, so 666 with 027 masked gives 640. A umask of 022 yields 644, 002 yields 664, and 777 would leave no permissions at all.

Correct answer: A — man -k partition

man -k, equivalent to apropos, searches the manual page index by keyword, which is how you find a command when you do not know its name. man with a name opens one page, info reads a different documentation format, and listing the man directory does not search descriptions.

Correct answer: A — vgextend vg0 /dev/sdc

vgextend grows a volume group by adding physical volumes to it. vgreduce removes one, lvextend grows a logical volume rather than a group, and pvremove wipes LVM metadata from a device.

Correct answer: A, B — /etc/passwd, which records the primary group ID · /etc/group, which lists supplementary members

The fourth field of a passwd entry is the primary GID, and group entries list additional members. shadow holds password hashes, sudoers configures privilege escalation, and skel holds the template for new home directories.

Correct answer: A — xfs_growfs /mountpoint

XFS is grown with xfs_growfs and, unlike ext4, cannot be shrunk. resize2fs and tune2fs are ext filesystem tools, and xfs_repair fixes damage rather than resizing.

Correct answer: A — semanage fcontext -a -t httpd_sys_content_t '/srv/web(/.*)?' then restorecon -Rv /srv/web

semanage records the rule in policy so relabelling reproduces it, and restorecon applies it now. chcon alone is lost on a full relabel, disabling enforcement is not a fix, and world-writable permissions are a serious security problem.

Correct answer: A — autofs

autofs mounts a filesystem when its path is accessed and unmounts it when idle, which suits home directories on NFS. chronyd synchronises time, firewalld manages the firewall, and tuned applies performance profiles.

Correct answer: A — nmcli connection modify ens192 ipv4.method manual ipv4.addresses 10.0.0.10/24

connection modify writes the addressing settings into the stored profile, which then needs bringing up to take effect. disconnect drops the interface, general status summarises NetworkManager, and radio controls wireless.

Correct answer: A — /etc/hosts

hosts holds local static mappings, which nsswitch.conf normally consults before DNS. resolv.conf lists nameservers, hostname stores the system's own name, and nsswitch.conf defines the lookup order rather than the mappings themselves.

Correct answer: A — Interrupt the bootloader, append rd.break to the kernel line, remount sysroot read-write, chroot, set the password, and relabel SELinux

The documented procedure boots into the initramfs shell, remounts the root filesystem writable, changes the password in a chroot, and triggers an SELinux relabel so the shadow file's context stays correct. An unprivileged user cannot change root's password or edit shadow, and reinstalling is unnecessary.

Correct answer: A — tuned-adm profile virtual-guest

tuned-adm selects a tuning profile that adjusts kernel and device parameters for the workload type. set-default changes the systemd boot target, sysctl -w sets an individual kernel parameter, and grubby edits bootloader entries.

Correct answer: A — A zone

firewalld zones bind interfaces and source addresses to a trust level with its own service and port rules. Chains are an iptables concept, profiles belong to tuned or NetworkManager, and contexts are an SELinux concept.

Correct answer: A — useradd -r -s /sbin/nologin appsvc

The -r flag creates a system account with a UID from the system range and nologin prevents interactive login. Creating a bash account with a home directory is what you do for a person, and the other options grant or restore an interactive shell.

Correct answer: A — dnf module enable nodejs:20

Modules let a distribution ship several versions of the same software, and enabling a stream selects which one dnf installs from. Installing a package name may not select the intended stream, rpm -U upgrades a local package file, and group install installs a package group.

Correct answer: A — chronyd, configured in /etc/chrony.conf

chrony replaced ntpd as the default NTP implementation on RHEL and is configured through chrony.conf. cronie provides cron scheduling and rsyslog handles logging.

Correct answer: A — #!/bin/bash

The shebang must be the first two characters followed by the interpreter path. A comment, a missing hash, or a double slash are not recognised by the kernel as an interpreter directive.

Correct answer: A, B — Disable direct root login in sshd_config · Use key-based authentication and disable password authentication

Removing direct root login and password authentication closes the two paths attackers brute-force most. Empty passwords, a disabled firewall, and shared accounts each remove a control or destroy accountability.

Correct answer: A — rpm -qf /usr/sbin/sshd

rpm -qf queries which package provides a given file path. rpm -ql lists the files in a named package, dnf list installed enumerates packages without mapping a path, and which only locates the binary.

Correct answer: A — chage -M 60 dave

chage -M sets the maximum password age in days. The -l option only lists current settings, and passwd -l and usermod -L both lock the account.

Correct answer: A — 30 2 * * * /usr/local/bin/backup.sh

The field order is minute, hour, day of month, month, day of week, so 30 2 means 02:30 every day. The second option reads as minute 2 of hour 30, the third sets day and month fields, and the fourth restricts to Mondays.

Correct answer: A — nmcli connection up ens192

Bringing the connection up reapplies the saved profile so the new settings take effect. delete removes the profile, show lists profiles, and restarting sshd is unrelated to network configuration.

Correct answer: A — dnf install httpd

dnf resolves dependencies from configured repositories, which rpm does not do. apt and zypper belong to Debian and SUSE systems respectively.

Correct answer: A — firewall-cmd --zone=public --permanent --add-port=8080/tcp then --reload

The permanent flag writes the rule and reload activates it, and the port must include its protocol. A runtime-only rule is lost on reload, a raw iptables rule is not persisted, and disabling the firewall removes all protection.

Correct answer: A — dmesg

dmesg prints kernel messages including device detection and driver errors. last shows login history, who shows current sessions, and id shows the current user's identity.

Correct answer: A — Permissive

Permissive mode records the denials that would have occurred so you can collect them all before returning to enforcing. Enforcing blocks and logs, disabled stops labelling entirely, and targeted is a policy type rather than a mode.

Correct answer: A, B — tar -czf backup.tar.gz /data · tar -xzf backup.tar.gz -C /restore

c creates and x extracts, with z applying gzip and -C choosing the extraction directory. gzip alone handles single files, cpio uses a different archive format, and zip produces a zip archive.

Correct answer: A — cp "$src" /backup/

Double quotes prevent word splitting and glob expansion while still substituting the variable. Unquoted expansion splits on whitespace, single quotes prevent substitution entirely, and the last form is a syntax error.

Correct answer: A, B — dnf check-update --security · dnf update --security

check-update lists what is available and update applies it, both filtered to security advisories. Erasing packages while ignoring dependencies is dangerous, history undo reverses a transaction, and clean all removes cached metadata.

Correct answer: A, B — setfacl -m u:carol:rw /data/report.txt · getfacl /data/report.txt

setfacl adds the named-user entry and getfacl displays the resulting ACL. chmod would grant access to everyone, chown transfers ownership rather than adding an entry, and umask affects default permissions on newly created files.

Correct answer: A — at 23:00

The at command queues a single execution at a specified time, whereas cron is for repeating schedules. Enabling a unit affects boot behaviour, and nohup runs a command immediately in the background.

Correct answer: A — cp -a /src /dst

The archive flag implies recursion and preserves attributes and links. Plain -r copies recursively without preserving all attributes, mv relocates rather than copies, and ln creates a link.

Correct answer: A — pvcreate /dev/sdb, vgcreate vg0 /dev/sdb, lvcreate -L 10G -n lv_data vg0

LVM is layered: a physical volume, then a volume group built from it, then logical volumes carved out of the group. The reversed order is impossible, formatting the raw disk first bypasses LVM, and vgextend with pvremove modifies or removes storage rather than creating it.

Correct answer: A — An fstab entry with the _netdev and nofail options

_netdev defers the mount until networking is up and nofail prevents a failure from blocking the boot. defaults alone can stall the boot, a manual mount is not automatic, and hosts entries only resolve names.

Correct answer: A — userdel -r erin

The -r flag removes the home directory and mail spool along with the account. Plain userdel leaves the home directory behind, usermod changes the home path without deleting anything, and groupdel removes a group.

Correct answer: A — timedatectl set-timezone Europe/London

timedatectl updates /etc/localtime and the persistent configuration. date sets the clock rather than the zone, exporting TZ affects only the current shell, and hwclock synchronises the hardware clock.

Correct answer: A — ssh -p 2222 admin@host

ssh uses a lowercase -p for the port, whereas scp uses an uppercase -P. scp copies files rather than opening a shell, and telnet is an unencrypted protocol that should not be used.

Correct answer: A — [ -f /var/run/app.pid ]

-f tests for an existing regular file. -d tests for a directory, -z tests whether a string is empty, and -x tests the execute permission.

Correct answer: A — grep '^root' /etc/passwd

The caret anchors the pattern to the start of the line. The dollar anchors to the end, an unanchored pattern matches anywhere, and -v inverts the match.

Correct answer: A — parted /dev/sdb

parted creates and manipulates partition tables including GPT. mkfs formats an existing partition, mount attaches a filesystem, and lsblk only reports the layout.

Correct answer: A — mkfs.xfs /dev/vg0/lv_data

mkfs.xfs writes a new XFS filesystem. mkfs.vfat creates a FAT filesystem, xfs_repair repairs an existing one, and xfs_info reports geometry.