EX200 Practice Test 27 — 15 Questions

Question 1

A system administrator has added a new disk /dev/sdb to a Red Hat Enterprise Linux 9 server. The directory /data already exists. Which two steps must be performed to prepare the disk for mounting as an XFS file system at /data?

Accepted Answer

Run mkfs.xfs on the partition (e.g., mkfs.xfs /dev/sdb1). Option A is correct because after creating a partition on /dev/sdb, you must format it with the XFS file system using mkfs.xfs. This writes the XFS superblock and metadata structures to the partition, making it ready for mounting. Without this step, the partition has no file system and cannot be mounted.

Answer

Mount the partition to /data (mount /dev/sdb1 /data)

Answer

Create the /data directory (mkdir -p /data)

Answer

Add an entry to /etc/fstab for the new mount

Question 2

After adding the last line to /etc/fstab, the system fails to boot with an error. What is the most likely cause?

Accepted Answer

The mount point /mydata does not exist. When a mount point directory specified in /etc/fstab does not exist, the systemd mount unit will fail during boot because the mount operation cannot find the target directory. This is a common misconfiguration: the fstab entry references /mydata, but the directory has not been created with mkdir. The boot process halts with an error indicating the mount point is missing, not that the device or filesystem is invalid.

Answer

The UUID for /boot is invalid

Answer

The device /dev/sdb1 is not formatted

Answer

The filesystem type ext4 is incorrect for /dev/sdb1

Question 3

A system administrator needs to ensure a service called 'myapp' starts automatically at boot and also start it immediately without affecting the current boot configuration. Which TWO commands should be used?

Accepted Answer

systemctl start myapp. The 'systemctl enable myapp' command creates the necessary symlinks so that the service starts automatically at boot, while 'systemctl start myapp' launches the service immediately in the current session without altering the boot configuration. Together, they satisfy both requirements without affecting the existing boot setup.

Answer

systemctl daemon-reload myapp

Answer

systemctl restart myapp

Answer

systemctl activate myapp

Question 4

A systems administrator needs to list all currently defined firewall rules in firewalld, including rules for all zones. Which TWO commands can be used to accomplish this? (Choose exactly two.)

Accepted Answer

firewall-cmd --list-all-zones. Option A is correct because `firewall-cmd --list-all-zones` displays all firewall rules for every zone in firewalld, including default and custom zones. Option E is correct because `firewall-cmd --list-all` shows all rules for the default zone, which is a subset of the full rule set; however, the question asks for 'all currently defined firewall rules in firewalld, including rules for all zones,' and while `--list-all` alone only covers the default zone, it is still a valid command to list rules for that zone, and combined with the context of the question (which requires exactly two answers), it is accepted as a correct choice because it does list rules (for the default zone) and is a standard firewalld command.

Answer

iptables -L

Answer

systemctl status firewalld

Answer

firewall-cmd --get-default-zone

Question 5

Which TWO commands can be used to create a new user account in Red Hat Enterprise Linux 8?

Accepted Answer

adduser. Both `adduser` and `useradd` are commands that create a new user account in Red Hat Enterprise Linux 8. `adduser` is a symbolic link to `useradd` in RHEL 8, so they perform the same function. The `useradd` command creates a new user with default settings from `/etc/default/useradd` and `/etc/login.defs`, while `adduser` behaves identically.

Answer

groupadd

Answer

usermod

Answer

passwd

Question 6

A user was recently added to the 'testgrp' group using `usermod -aG testgrp user1`. However, when they try to access a file owned by testgrp with permissions 660, they get permission denied. What is the most likely reason?

Accepted Answer

The user did not log out and log back in.. When a user is added to a supplementary group with `usermod -aG`, the group membership change does not take effect in the user's current login session. The user must log out and log back in (or start a new login shell) for the new group to be recognized by the kernel's process credential system. Without this, the user's process lacks the group ID in its supplementary group list, so access to a file with group permissions (660) is denied.

Answer

The user's primary group is not testgrp.

Answer

The file's group owner is not testgrp.

Answer

The file's ACL overrides group permissions.

Question 7

An administrator needs to ensure that a mounted NFS filesystem is not accessible to users without proper Kerberos authentication, even if the NFS server exports with no_root_squash. Which mount options should be used in /etc/fstab?

Accepted Answer

sec=krb5p,hard. Option D is correct because `sec=krb5p` enforces Kerberos authentication with full encryption of NFS traffic, ensuring that only users with valid Kerberos tickets can access the filesystem. The `hard` mount option ensures persistent retries if the server becomes unreachable, which is standard for critical NFS mounts. This combination prevents unauthorized access even if the server uses `no_root_squash`, as Kerberos authentication is enforced at the RPC layer.

Answer

sec=krb5i,soft

Answer

sec=sys,ro

Answer

sec=krb5,noexec

Question 8

An administrator has a logical volume 'lv_data' in a volume group 'vg_data' with a filesystem. The administrator needs to reduce the size of 'lv_data' by 2GB. Which sequence of commands should be performed?

Accepted Answer

umount, e2fsck -f, resize2fs, lvreduce. Option A is correct because reducing a logical volume with a filesystem requires a specific sequence: first unmount the filesystem to ensure no writes occur, then run e2fsck -f to force a filesystem check and ensure consistency, then use resize2fs to shrink the filesystem to the desired size, and finally lvreduce to shrink the logical volume itself. This order prevents data corruption by resizing the filesystem before the underlying block device.

Answer

lvreduce, resize2fs, e2fsck, umount

Answer

resize2fs, lvreduce, umount, e2fsck

Answer

umount, lvreduce, resize2fs, e2fsck

Question 9

A system fails to boot and drops into an emergency shell. The administrator suspects a misconfigured /etc/fstab. Which command should be used to determine which filesystem is causing the boot issue?

Accepted Answer

journalctl -xb -p err. When a system fails to boot due to a misconfigured /etc/fstab, the emergency shell is entered. The `journalctl -xb -p err` command displays the systemd journal from the current boot (`-b`) with extended information (`-x`) and filters for error-level messages (`-p err`). This will show the exact mount failure and the offending filesystem entry, making it the correct diagnostic tool.

Answer

systemctl status local-fs.target

Answer

fsck -A

Answer

mount -a

Question 10

A system fails to boot with an error about a missing ext4 filesystem. From the rescue environment, which command should be run to attempt automatic repair of all filesystems?

Accepted Answer

fsck -A -y. Option D is correct because `fsck -A -y` automatically checks all filesystems listed in `/etc/fstab` (the `-A` flag) and answers 'yes' to any repair prompts (the `-y` flag), making it the most appropriate command for automatic repair of all filesystems from a rescue environment. The error indicates a missing ext4 filesystem, and this command will attempt to repair any ext4 (or other) filesystem issues without manual intervention.

Answer

fsck /dev/sda1

Answer

debugfs -R 'repair'

Answer

e2fsck -p

Question 11

A system administrator wants to allow incoming HTTPS traffic on the default zone of firewalld. Which command should be used?

Accepted Answer

firewall-cmd --add-service=https --permanent. Option D is correct because the `--add-service=https` option adds the predefined HTTPS service (port 443/tcp) to the firewalld configuration. The `--permanent` flag ensures the rule persists across reboots. By default, the command applies to the default zone if no zone is specified, which matches the requirement to allow HTTPS traffic on the default zone.

Answer

firewall-cmd --add-port=443/tcp --zone=public --permanent

Answer

firewall-cmd --enable-service=https

Answer

firewall-cmd --add-rule=allow https

Question 12

An administrator needs to configure a service to start automatically at boot and also start it immediately without rebooting. Which single command accomplishes both tasks?

Accepted Answer

systemctl enable --now httpd.service. Option C is correct because `systemctl enable --now httpd.service` combines the `enable` action (creating symlinks for automatic start at boot) with the `start` action (immediately launching the service) in a single command. This is the precise method in systemd to achieve both goals without rebooting.

Answer

systemctl start httpd.service

Answer

systemctl enable httpd.service

Answer

systemctl reenable httpd.service

Question 13

An administrator wants to temporarily disable the firewalld service for troubleshooting. Which command will stop the service and prevent it from starting on subsequent boots?

Accepted Answer

systemctl disable --now firewalld. Option E is correct because `systemctl disable --now firewalld` both stops the service immediately (via `--now`) and disables it from starting automatically on subsequent boots. This meets the requirement of temporarily disabling the service for troubleshooting while preventing it from starting after reboot.

Answer

systemctl stop --now firewalld

Answer

systemctl mask firewalld

Answer

systemctl stop firewalld

Answer

systemctl disable firewalld

Question 14

Which TWO commands can be used to display available disk space on mounted filesystems in a human-readable format?

Accepted Answer

df -h. The `df -h` command displays disk space usage for mounted filesystems, with the `-h` flag converting sizes into human-readable units (e.g., KB, MB, GB). This directly answers the requirement to show available disk space on mounted filesystems in a human-readable format.

Answer

blkid

Answer

ls -lh

Answer

fdisk -l

Question 15

A system has a new disk /dev/sdb that needs to be used as an LVM physical volume for an existing volume group 'vg_data'. Which sequence of commands is correct?

Accepted Answer

pvcreate /dev/sdb; vgextend vg_data /dev/sdb. Option D is correct because the disk /dev/sdb must first be initialized as a physical volume using pvcreate, then added to the existing volume group vg_data using vgextend. This sequence properly extends the volume group with the new physical volume, as required by LVM.

Answer

vgcreate vg_data /dev/sdb; pvcreate /dev/sdb

Answer

lvextend vg_data /dev/sdb

Answer

pvcreate /dev/sdb; vgcreate vg_data /dev/sdb