EX200 Practice Exam 2 — 20 Questions

Question 1

A team wants to run a container as a non-root user inside the container for security. Which instruction should be included in the Containerfile?

Accepted Answer

USER. The USER instruction in a Containerfile (Dockerfile) sets the user name or UID to use when running the container and for any subsequent RUN, CMD, or ENTRYPOINT instructions. By default, containers run as root (UID 0), which poses a security risk. Using USER to switch to a non-root user (e.g., USER 1001) ensures the container process runs with reduced privileges, aligning with the principle of least privilege.

Answer

PODMAN_USER

Answer

ENV USER

Answer

RUN useradd

Question 2

A Red Hat Enterprise Linux 9 server has an LVM volume group 'vg01' that contains two physical volumes: /dev/sda2 and /dev/sdb1. After a reboot, the system fails to activate the volume group. The administrator runs 'pvdisplay' and sees one physical volume as 'unknown device'. What is the most likely cause?

Accepted Answer

The LVM filter in /etc/lvm/lvm.conf is excluding /dev/sdb1. The LVM filter in /etc/lvm/lvm.conf controls which devices LVM scans during activation. If the filter excludes /dev/sdb1, LVM will not recognize that physical volume, causing the volume group to fail activation. The 'unknown device' status indicates LVM cannot access the device metadata, not that the device is missing or corrupted.

Answer

The physical volume is corrupted and needs to be restored from backup

Answer

The filesystem on the logical volume has become corrupted, preventing LVM metadata access

Answer

The UUID of the physical volume has changed due to a disk replacement

Question 3

An administrator receives an alert that a process named 'apache2' is consuming excessive CPU. The administrator needs to identify the PID of the process and then change its priority to the lowest possible value (least favorable scheduling). Which sequence of commands should be used?

Accepted Answer

pidof apache2; renice -n 19 -p . `pidof apache2` retrieves the PID of the apache2 process, and `renice -n 19 -p ` sets the priority to the lowest possible (least favorable) scheduling value. In Linux, `renice` accepts nice values from -20 (highest priority) to 19 (lowest priority), so 19 is the correct value for the least favorable scheduling.

Answer

pidof apache2; renice -n 20 -p <PID>

Answer

ps -C apache2 -o pid=; renice -n -20 -p <PID>

Answer

ps aux | grep apache2; nice -n 19 <PID>

Question 4

You are managing a Red Hat Enterprise Linux 8 server that hosts backup scripts. A user named 'backup' (UID 1005) is a member of the 'backup' group. The directory /var/backups is owned by root:backup with permissions 775. The 'backup' user needs to create files in this directory. However, when the user attempts to create a file, they receive 'Permission denied'. You verify that 'backup' is indeed listed in the backup group in /etc/group. The user's current shell was started after their last login. Which of the following is the most likely cause and solution?

Accepted Answer

The user needs to log out and log back in to refresh their group membership.. The user 'backup' is already a member of the 'backup' group in /etc/group, but the current shell session was started before the group membership was added or refreshed. On Linux, group membership is determined at login time by the PAM modules; simply adding a user to a group does not affect already running processes. The user must log out and log back in (or start a new login shell) to acquire the new group membership via the initgroups() system call, which populates the process's supplementary group list.

Answer

The directory lacks the setgid bit; set it with 'chmod g+s /var/backups'.

Answer

The user's umask is too restrictive, preventing file creation. Change the umask to 002.

Answer

The user should use 'newgrp backup' to switch to the backup group temporarily.

Question 5

Refer to the exhibit. An administrator needs to create a new 5GB filesystem for /var/log. Which step is required?

Accepted Answer

Add /dev/sdc as a physical volume, extend vg00, create a logical volume, and format. To create a new filesystem for /var/log using available space on /dev/sdc, the disk must first be added as a physical volume (pvcreate), then added to the existing volume group vg00 (vgextend). After extending the VG, a new logical volume can be created (lvcreate) and formatted with a filesystem (e.g., mkfs.xfs). This approach leverages LVM's flexibility to allocate space from multiple physical volumes without requiring a separate volume group or partition manipulation.

Answer

Create a new partition on /dev/sdc and format with xfs

Answer

Shrink /home to free space in vg00 and create a new LV

Answer

Create a new volume group using /dev/sdb

Question 6

A company needs to create a user account for a temporary contractor who will work for exactly 90 days. The account must be automatically disabled after 90 days. Which command should the administrator use?

Accepted Answer

useradd -e $(date -d '+90 days' +%Y-%m-%d) contractor. The `-e` (expiration date) option sets the date on which the user account will be disabled. Using `$(date -d '+90 days' +%Y-%m-%d)` dynamically calculates the exact date 90 days from today in YYYY-MM-DD format, which meets the requirement for automatic disable after exactly 90 days.

Answer

useradd -f 90 contractor

Answer

useradd -e 90 contractor

Answer

useradd -f 90 -e 0 contractor

Question 7

A user named jdoe is receiving 'Permission denied' errors when trying to access a file owned by root with permissions 644. The user is a member of the root group. What is the most likely cause?

Accepted Answer

The directory containing the file lacks execute permission for the group or others.. The file has permissions 644, meaning the owner (root) has read/write, and the group (root) and others have read-only access. Since jdoe is a member of the root group, the file's group read permission should allow access. However, to traverse a directory and access any file within it, the user needs execute (x) permission on that directory. If the directory lacks execute for the group or others, jdoe will get 'Permission denied' even if the file permissions are correct.

Answer

The file's group owner is not root.

Answer

The file's read permission is not granted to the root group.

Answer

The user needs to be added to the root group again.

Question 8

An administrator needs to create a network bond interface 'bond0' with two slave interfaces 'eth0' and 'eth1' using active-backup mode. Which set of commands is correct?

Accepted Answer

nmcli con add type bond ifname bond0 mode active-backup; nmcli con add type bond-slave ifname eth0 master bond0; nmcli con add type bond-slave ifname eth1 master bond0. The commands create a bond interface with active-backup mode using nmcli. First, `nmcli con add type bond ifname bond0 mode active-backup` creates the bond with the required mode. Then, `nmcli con add type bond-slave ifname eth0 master bond0` and similarly for eth1 add the slave interfaces. This is the correct set of commands that fulfills the requirement. Option A uses an alternative syntax but does not set the mode. Option B involves manual editing, and option C uses teamd, which is for teaming, not bonding.

Answer

nmcli con add type bond ifname bond0; nmcli con add type ethernet ifname eth0 master bond0 slave-type bond

Answer

Edit /etc/sysconfig/network-scripts/ifcfg-bond0 and ifcfg-eth0 manually

Answer

teamd -d -c '{"device":"bond0","runner":{"name":"activebackup"},"ports":{"eth0":{},"eth1":{}}}'

Question 9

Refer to the exhibit. An administrator needs to create a 1.2 TiB logical volume named 'data' in volume group 'myvg' and mount it persistently at /data. Which sequence of commands should be used?

Accepted Answer

lvcreate -L 1.2T -n data myvg
mkfs.xfs /dev/myvg/data
echo '/dev/myvg/data /data xfs defaults 0 0' >> /etc/fstab
mount -a. It creates a logical volume of exactly 1.2 TiB using the valid -L 1.2T size specification. LVM's -L option accepts floating-point values with suffixes like T for TiB. The volume is formatted with XFS (default for RHEL 8+), a correct fstab entry is added with /dev/myvg/data, and mount -a mounts it persistently. Option D uses 1200G, which yields approximately 1.17 TiB, not the required 1.2 TiB.

Answer

lvcreate -L 1.2T -n data myvg
mkfs.ext4 /dev/myvg/data
echo '/dev/myvg/data /data ext4 defaults 0 0' >> /etc/fstab
mount -a

Answer

lvcreate -l 100%FREE -n data myvg
mkfs.xfs /dev/myvg/data
echo '/dev/mapper/myvg-data /data xfs defaults 0 0' >> /etc/fstab
mount -a

Answer

lvcreate -L 1200G -n data myvg
mkfs.ext4 /dev/myvg/data
echo '/dev/myvg/data /data ext4 defaults 0 0' >> /etc/fstab
mount -a

Question 10

An administrator writes a script that uses the 'set -e' option at the top. What is the primary effect of this option?

Accepted Answer

It exits the script immediately if a command fails. The 'set -e' option instructs the shell to exit immediately if any command or pipeline returns a non-zero exit status (i.e., fails). This is commonly used in scripts to prevent execution from continuing after an error, which could lead to unpredictable behavior or data corruption. It does not affect variable handling, command printing, or debug verbosity.

Answer

It treats unset variables as an error

Answer

It prints each command before execution

Answer

It enables debug mode with verbose output

Question 11

A filesystem is reported as 'read-only' after a system crash. The admin runs fsck and sees 'clean' status. What is the most likely reason it remains read-only?

Accepted Answer

The filesystem is XFS, and fsck does not repair XFS.. If fsck reports 'clean', it means no errors were found in the filesystem's journal, so option D is incorrect. Option C is correct because XFS filesystems cannot be repaired by fsck; they require xfs_repair. Running fsck on an XFS filesystem simply reports the clean flag without performing a real check, leaving the kernel to enforce read-only status if any issues persist.

Answer

fsck cannot fix errors on ext4 filesystems.

Answer

The filesystem is still mounted; fsck cannot fix it while mounted.

Answer

fsck detected errors but did not fix them automatically.

Question 12

A script needs to be run at system boot for a specific user. Which method ensures the script runs with that user's environment?

Accepted Answer

Create a systemd user unit in ~/.config/systemd/user/. Systemd user units, placed in ~/.config/systemd/user/, are executed in the user's own session context, inheriting the user's environment variables, PATH, and D-Bus session. This ensures the script runs with the specific user's environment at boot, as systemd starts the user manager (systemd --user) early in the boot process for each enabled user.

Answer

Place the script in /etc/rc.d/rc.local

Answer

Add an entry to ~/.xprofile

Answer

Add the script to the user's crontab with @reboot

Question 13

A system administrator is troubleshooting a container that fails to start with the error: 'Error: cannot start container: listen tcp4 :80: bind: address already in use'. The container is intended to serve HTTP traffic on port 80. What is the most appropriate first step to resolve this issue?

Accepted Answer

Check which process is using port 80 and either stop that process or use a different host port. The error 'address already in use' indicates that port 80 on the host is already occupied by another process. The correct first step is to identify that process using commands like `ss -tlnp` or `lsof -i :80` and either stop it or map the container to a different host port (e.g., `-p 8080:80`). This directly resolves the binding conflict without risking data loss or unintended behavior.

Answer

Add --force to the podman run command

Answer

Add --replace to the podman run command

Answer

Use --net=host to bypass the port mapping

Question 14

Refer to the exhibit. A user named 'carol' has been added to the system with the command useradd -G wheel carol. Which line in /etc/group will confirm that carol is now a member of the wheel group?

Accepted Answer

wheel:x:10:root,alice,bob,carol. The `useradd -G wheel carol` command adds 'carol' to the supplementary group 'wheel', and the `/etc/group` file lists supplementary members as a comma-separated list with no trailing comma. The line `wheel:x:10:root,alice,bob,carol` shows 'carol' appended after the existing members, which matches the expected format.

Answer

wheel:x:10:carol,root,alice,bob

Answer

wheel:x:10:root,alice,bob,carol,

Answer

wheel:x:10:root,alice,bob carol

Question 15

A developer runs the script shown in the exhibit and always sees 'Success' printed, even when the previous command fails. What is the most likely cause?

Accepted Answer

The $? variable captures the exit status of the [[ command, not the intended command. The `[[ ]]` conditional construct is a shell keyword that itself produces an exit status. When `$?` is checked immediately after `[[ ]]`, it captures the exit status of the `[[ ]]` evaluation (which is 0 if the condition is true, 1 if false), not the exit status of the command that was run before the `[[ ]]`. Since the developer always sees 'Success' printed, the `[[ ]]` condition must be evaluating to true (exit status 0), causing `$?` to be 0 and the script to always take the success path, regardless of the actual previous command's result.

Answer

The [[ ]] syntax always evaluates to true

Answer

The $? variable is only set after external commands, not builtins

Answer

The $? variable always returns 0 in a conditional

Question 16

A new employee named asmith needs a user account with a home directory and a specific UID of 1500. Which command accomplishes this?

Accepted Answer

useradd -m -u 1500 asmith. `useradd -m -u 1500 asmith` creates the user asmith with a home directory (via `-m`) and assigns a specific UID of 1500 (via `-u`). The `-m` flag ensures the home directory is created if it does not exist, which is required by the question.

Answer

adduser -uid 1500 asmith

Answer

useradd -h /home/asmith -u 1500 asmith

Answer

useradd -d /home/asmith -U 1500 asmith

Question 17

An administrator wants to ensure that any new user accounts created on the system have a default primary group matching the username. What change is needed?

Accepted Answer

Set USERGROUPS_ENAB to yes in /etc/login.defs. Setting USERGROUPS_ENAB to yes in /etc/login.defs instructs the useradd command to automatically create a private group with the same name as the new user and assign it as the user's primary group. This is the default behavior in Red Hat Enterprise Linux and ensures that each new user has a matching primary group without manual intervention.

Answer

Set GROUP to same name in /etc/default/useradd

Answer

Set USERGROUPS_ENAB to no; then create user with -g

Answer

Set CREATE_HOME to yes in /etc/login.defs

Question 18

A system administrator needs to change the primary group of an existing user to a group that already exists. Which command should be used?

Accepted Answer

usermod -g existinggroup username. The `usermod -g` command changes the primary group of an existing user to a specified group that already exists on the system. The `-g` option sets the initial login group (GID) for the user, which must be a valid group name or GID from `/etc/group`.

Answer

groupmod -g existinggroup username

Answer

usermod -p existinggroup username

Answer

usermod -G existinggroup username

Question 19

A server has been compromised, and the administrator suspects an unauthorized user account may have been created. Which file should be examined to list all local user accounts?

Accepted Answer

/etc/passwd. The /etc/passwd file is the primary local user account database on Linux systems, listing all user accounts with fields such as username, UID, GID, GECOS, home directory, and login shell. Examining this file reveals every local user account, including any unauthorized ones that may have been created, because each account must have an entry here to be recognized by the system.

Answer

/etc/shadow

Answer

/etc/shells

Answer

/etc/login.defs

Question 20

An administrator needs to schedule a script to run every Monday, Wednesday, and Friday at 2:30 PM. Which cron expression should be used?

Accepted Answer

30 14 * * 1,3,5. Cron uses five fields (minute, hour, day-of-month, month, day-of-week). 2:30 PM is 14:30 in 24-hour format, so minute=30 and hour=14. The day-of-week field uses 0-7 (0 and 7 = Sunday), with Monday=1, Wednesday=3, Friday=5. The asterisks for day-of-month and month mean 'every day' and 'every month', so the expression `30 14 * * 1,3,5` runs the script at 2:30 PM on Monday, Wednesday, and Friday.

Answer

30 14 * * 1-5

Answer

14 30 * * 1,3,5

Answer

30 14 * * 0,2,4