EX200 Practice Test 27 — 15 Questions

Question 1

A system administrator tries to mount a filesystem but receives the error: 'mount: /dev/sdb1 is already mounted or /data busy'. The filesystem is not listed in the mount output. What is the most likely cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The mount point /data is in use by a process. The error message 'mount: /dev/sdb1 is already mounted or /data busy' indicates that the mount point /data is currently in use by a process, preventing the mount operation. Even though the filesystem is not listed in the mount output, a process may have an open file descriptor or be using /data as its current working directory, which keeps the directory busy. The 'lsof' or 'fuser' commands can be used to identify the offending process.

Answer

The kernel does not have the filesystem driver loaded

Answer

The device is already mounted on another mount point

Answer

The filesystem is corrupted

Question 2

A system administrator needs to add a new 10GB disk to an existing volume group 'vgdata' to extend logical volumes. Which of the following is the correct sequence of commands?

Accepted Answer

pvcreate /dev/sdb, vgextend vgdata /dev/sdb, lvextend. The proper sequence to add a new disk to an existing volume group is: first create a physical volume with `pvcreate /dev/sdb`, then extend the volume group with `vgextend vgdata /dev/sdb`, and finally extend the logical volume with `lvextend`. This order ensures the disk is initialized as a PV before it can be added to the VG, and the VG must have the new PV before the LV can be extended.

Answer

vgextend vgdata /dev/sdb, pvcreate /dev/sdb, lvextend

Answer

pvcreate /dev/sdb, lvextend, vgextend vgdata /dev/sdb

Answer

lvextend, vgextend vgdata /dev/sdb, pvcreate /dev/sdb

Question 3

A system administrator needs to find all regular files larger than 10MB in /var/log. Which find command should they use?

Accepted Answer

find /var/log -type f -size +10M. It uses `-type f` to select only regular files and `-size +10M` to match files larger than 10 megabytes. The `+` prefix in the `-size` test means 'greater than', which is the correct syntax for finding files exceeding a given size.

Answer

find /var/log -type f -size -10M

Answer

find /var/log -type d -size +10M

Answer

find /var/log -type f -size 10M

Question 4

Alice tries to run 'sudo less /var/log/messages' and gets 'Sorry, user alice is not allowed to execute /usr/bin/less /var/log/messages as root on this host.' Why?

Accepted Answer

The sudoers allows only specific commands with specific arguments. Sudoers rules can restrict commands to specific arguments. The error message indicates that the sudoers configuration explicitly allows 'less' only with certain arguments (or none), and the attempt to run 'less /var/log/messages' violates that restriction. Sudo matches both the command path and the argument list against the sudoers entries, and if the arguments do not match, access is denied.

Answer

The command path must exactly match, including arguments

Answer

The secure_path does not include /usr/bin

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The /var/log/messages file does not exist

Question 5

Which TWO of the following are correct statements about exit codes in shell scripts?

Accepted Answer

A non-zero exit code usually indicates a failure. In shell scripting, exit codes are integers from 0 to 255. An exit code of 0 conventionally indicates success, while any non-zero value (1–255) indicates a failure or error condition. Option B is correct because a non-zero exit code usually signals that the command or script did not complete successfully.

Answer

An exit code of 1 means success

Answer

An exit code of -1 indicates a system error

Answer

If no 'exit' is used, the script exits with code 0

Question 6

A user reports that they cannot start a service. Which command would an administrator use to view the service's journal logs since last boot?

Accepted Answer

journalctl -u service -b. `journalctl -u service -b` combines the `-u` flag to filter logs for a specific systemd unit (the service) with the `-b` flag to show only logs from the current boot. This is the precise command an administrator would use to view a service's journal logs since the last system start, directly addressing the user's inability to start the service.

Answer

journalctl -b

Answer

journalctl service

Answer

dmesg | grep service

Question 7

A system administrator is troubleshooting a RHEL 9 server that fails to boot and drops into emergency mode. The system console shows an error about mounting /dev/sdb1 on /data. The administrator enters emergency mode, checks /etc/fstab, and sees the line: /dev/sdb1 /data ext4 defaults 0 0. The /data directory exists but /dev/sdb1 is a partition on an external USB drive that was removed. The administrator needs the system to boot normally without the USB drive and plans to fix the mount configuration later. Which course of action should the administrator take?

Accepted Answer

Use a text editor to insert '#' at the beginning of the /dev/sdb1 line in /etc/fstab, then reboot.. Commenting out the /dev/sdb1 line in /etc/fstab with '#' prevents systemd from attempting to mount the missing device during boot, allowing the system to boot normally into multi-user.target. This is a safe, reversible change that does not delete the mount point or alter the filesystem, and it preserves the original configuration for later restoration.

Answer

Remove the line from /etc/fstab and run systemctl daemon-reload, then reboot.

Answer

Add the nofail option to the fstab line, then reboot.

Answer

Delete the /data directory and reboot.

Question 8

A system administrator needs to ensure that a specific kernel module 'usb_storage' is not loaded automatically during boot on a RHEL 9 system. Which configuration file should be modified to blacklist this module?

Accepted Answer

Add 'blacklist usb_storage' to /etc/modprobe.d/blacklist.conf. On RHEL 9, the recommended way to prevent a kernel module from loading automatically is to add a 'blacklist' directive in a file under /etc/modprobe.d/. The file /etc/modprobe.d/blacklist.conf is a conventional location for such blacklist entries. When modprobe processes this file, it will ignore the specified module during boot and when loading modules manually, effectively preventing usb_storage from being loaded.

Answer

Add 'blacklist usb_storage' to /etc/modules-load.d/usb_storage.conf

Answer

Add 'install usb_storage /bin/false' to /etc/sysconfig/modules/

Answer

Add 'blacklist usb_storage' to /etc/init.d/rc.local

Question 9

To allow a user to run a specific program with root privileges without providing the root password, which configuration file should be modified?

Accepted Answer

/etc/sudoers. The /etc/sudoers file is the correct configuration file to modify because it controls the sudo command, which allows specified users to execute programs with root privileges. By adding an entry such as `username ALL=(ALL) NOPASSWD: /path/to/program`, the user can run that specific program without being prompted for a password. This is the standard mechanism in Red Hat Enterprise Linux for granting passwordless privilege escalation.

Answer

/etc/passwd

Answer

/etc/security/limits.conf

Answer

/etc/sysconfig/sshd

Question 10

Which single command shows the UUID of a filesystem on /dev/sdb1?

Accepted Answer

blkid /dev/sdb1. The `blkid /dev/sdb1` command queries the libblkid library to read the filesystem metadata directly from the block device, displaying attributes including the UUID (Universally Unique Identifier) stored in the superblock. This is the standard, single-purpose command to retrieve the UUID of a specific partition.

Answer

df -h

Answer

mount

Answer

fdisk -l

Question 11

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 12

Which two statements about SELinux modes are correct? (Choose two.)

Accepted Answer

Permissive mode logs violations but does not deny actions.. SELinux permissive mode allows all actions but logs any violations that would have been denied in enforcing mode. Option D is correct because enforcing mode both logs violations and denies actions that violate the SELinux policy, providing full security enforcement.

Answer

Permissive mode denies actions but does not log.

Answer

Enforcing mode only logs violations but does not deny.

Answer

Disabled mode completely disables SELinux without requiring a reboot.

Question 13

Which TWO options to podman run can be used to persist data outside the container? (Select exactly two.)

Accepted Answer

--mount. The `--mount` option (A) and `-v` (D) are both used to mount host directories or volumes into a container, allowing data to persist outside the container's writable layer. `--mount` provides a more explicit syntax for specifying mount type, source, and destination, while `-v` is a shorter alias for `--volume` that also binds host paths or named volumes. Both ensure data survives container removal.

Answer

--read-only

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--tmpfs

Answer

--squash

Question 14

To mount an ext4 filesystem with the noatime option and remount read-only on errors, which file should be edited?

Accepted Answer

/etc/fstab. The /etc/fstab file is the system configuration file that defines how disk partitions, block devices, and remote filesystems should be mounted into the filesystem tree. To mount an ext4 filesystem with the noatime option and to remount it read-only on errors, you add the options 'noatime,errors=remount-ro' in the fourth field (mount options) of the corresponding entry in /etc/fstab. This ensures the options are applied automatically at boot and during subsequent mount operations.

Answer

/etc/mtab

Answer

/etc/sysconfig/network

Answer

/etc/rc.d/rc.local

Question 15

A containerized application writes logs to stdout. The administrator wants to view only the last 50 lines of logs from a container named 'app1'. Which command accomplishes this?

Accepted Answer

podman logs --tail 50 app1. The `podman logs --tail 50 app1` command is correct because `--tail` is the Podman option to specify the number of lines from the end of the log to display. This directly fulfills the requirement to view only the last 50 lines of logs from the container named 'app1'.

Answer

podman logs --lines 50 app1

Answer

podman logs app1

Answer

podman logs -n 50 app1