Scenario practice questions

A system is experiencing high CPU usage. The administrator suspects a process is stuck in an infinite loop. Which command can be used to identify the most CPU-intensive process in real-time?

Trap 1: lsof

lsof lists open files, not CPU usage.

Trap 2: ps aux

ps aux shows a snapshot of processes but does not update in real-time.

Trap 3: strace

strace traces system calls and signals, not a simple CPU usage monitor.

A
top
top displays real-time process activity and can sort by CPU usage.
B
lsof
Why wrong: lsof lists open files, not CPU usage.
C
ps aux
Why wrong: ps aux shows a snapshot of processes but does not update in real-time.
D
strace
Why wrong: strace traces system calls and signals, not a simple CPU usage monitor.

Question 2mediummultiple choice

An IT department runs a web server that stores user uploads on an ext4 filesystem on /dev/sdb1 mounted at /uploads. Recently, the partition has run out of space. The administrator checks with df -h and sees 100% usage. However, du -sh /uploads shows only 2GB used. The administrator suspects deleted files still held open by processes. Which command should be used to identify and resolve the issue?

Trap 1: rm -rf /uploads/* to clean all files

Deletes all uploaded data, not just open deleted files.

Trap 2: fsck /dev/sdb1 to repair filesystem

fsck does not reclaim space used by open deleted files.

Trap 3: resize2fs /dev/sdb1 to shrink filesystem

Shrinking requires free space; no space available.

A
rm -rf /uploads/* to clean all files
Why wrong: Deletes all uploaded data, not just open deleted files.
B
fsck /dev/sdb1 to repair filesystem
Why wrong: fsck does not reclaim space used by open deleted files.
C
resize2fs /dev/sdb1 to shrink filesystem
Why wrong: Shrinking requires free space; no space available.
D
lsof +L1 /uploads to find deleted open files, then kill processes
Identifies deleted files still in use; killing processes releases space.

Question 3easymulti select

Which THREE of the following are valid steps to create and mount an XFS filesystem on a new disk /dev/sdb?

Trap 1: mkfs.xfs -f /dev/sdb

Writing filesystem to whole disk, not a partition.

Trap 2: mount /dev/sdb1 /mnt

Mount command missing filesystem type; incorrect without fstab entry.

A
mkfs.xfs -f /dev/sdb
Why wrong: Writing filesystem to whole disk, not a partition.
B
mount -t xfs /dev/sdb1 /mnt
Correct mount command specifying XFS type.
C
mkfs.xfs /dev/sdb1
Creates XFS filesystem on partition.
D
mount /dev/sdb1 /mnt
Why wrong: Mount command missing filesystem type; incorrect without fstab entry.
E
echo "/dev/sdb1 /mnt xfs defaults 0 0" >> /etc/fstab
Adds entry to fstab for persistent mount.

Question 4mediummultiple choice

An administrator attempts to start a container with `podman run -d --name web -p 80:80 nginx`. The container fails to start and the logs show 'Error: cannot listen on port 80'. Which of the following is the most likely cause?

Trap 1: SELinux is blocking the port.

SELinux would generate an AVC denial message, not a port conflict error.

Trap 2: The container image is corrupt.

A corrupt image would produce errors related to image layers or checksums, not port binding.

Trap 3: The container is out of memory.

Out-of-memory conditions lead to container exits with OOM signals, not port listening errors.

A
SELinux is blocking the port.
Why wrong: SELinux would generate an AVC denial message, not a port conflict error.
B
The container image is corrupt.
Why wrong: A corrupt image would produce errors related to image layers or checksums, not port binding.
C
The container is out of memory.
Why wrong: Out-of-memory conditions lead to container exits with OOM signals, not port listening errors.
D
Port 80 is already in use on the host.
The error 'cannot listen on port 80' directly indicates the port is occupied by another process or container.

Question 5hardmultiple choice

A system has two logical volumes in the same volume group: 'lv_prod' (100% used) and 'lv_backup' (20% used). The administrator wants to allocate 5 GiB from 'lv_backup' to 'lv_prod' without unmounting any filesystems. Is this possible and why?

Trap 1: Yes, use lvreduce and lvextend while mounted; ext4 supports online…

Incorrect: ext4 does not support online shrink.

Trap 2: No, because LVM does not allow freeing extents from an LV while it…

Incorrect: LVM allows reduction but filesystem must be shrunk first.

Trap 3: Yes, use lvresize to move extents between LVs directly.

Incorrect: lvresize cannot move extents between LVs.

A
Yes, use lvreduce and lvextend while mounted; ext4 supports online shrinking.
Why wrong: Incorrect: ext4 does not support online shrink.
B
No, because LVM does not allow freeing extents from an LV while it is active.
Why wrong: Incorrect: LVM allows reduction but filesystem must be shrunk first.
C
No, because ext4 filesystems cannot be shrunk online; they must be unmounted.
Correct: ext4 requires unmount for shrink.
D
Yes, use lvresize to move extents between LVs directly.
Why wrong: Incorrect: lvresize cannot move extents between LVs.

Question 6easymultiple choice

A system administrator needs to create a file system on a new 10GB partition /dev/sdb1 for use with a database that requires high reliability and supports snapshots. Which file system type should be chosen?

Trap 1: ext4

ext4 supports snapshots but is not the default for RHEL 9 and is less optimal for large databases.

Trap 2: vfat

vfat does not support snapshots and is not suitable for a database.

Trap 3: btrfs

btrfs is not covered in RHCSA and is not the default file system in RHEL 9.

A
xfs
XFS is the default file system in RHEL 9, supports snapshots via LVM, and is optimized for large files.
B
ext4
Why wrong: ext4 supports snapshots but is not the default for RHEL 9 and is less optimal for large databases.
C
vfat
Why wrong: vfat does not support snapshots and is not suitable for a database.
D
btrfs
Why wrong: btrfs is not covered in RHCSA and is not the default file system in RHEL 9.

Question 7hardmultiple choice

Refer to the exhibit. The filesystem /var/www/html is mounted, but after a reboot, the directory is empty. What is the most likely cause?

Exhibit

# mkfs.ext4 /dev/vg_data/lv_web
mke2fs 1.45.6 (20-Mar-2020)
Creating filesystem with 1048576 4k blocks and 262144 inodes
Filesystem UUID: a1b2c3d4-e5f6-7890-abcd-ef1234567890
Superblock backups stored on blocks:
	32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

# mount /dev/vg_data/lv_web /var/www/html
# df -h /var/www/html
Filesystem                  Size  Used Avail Use% Mounted on
/dev/mapper/vg_data-lv_web  3.9G   16M  3.7G   1% /var/www/html
# cat /etc/fstab | grep lv_web
/dev/vg_data/lv_web /var/www/html ext4 defaults 0 0

Trap 1: The filesystem type is incorrectly specified as ext4 in fstab

Incorrect. The filesystem was created as ext4, so the type is correct.

Trap 2: The mount point /var/www/html does not exist after reboot

Incorrect. /var/www/html is a standard directory that exists.

Trap 3: The device path /dev/vg_data/lv_web is not persistent across reboots

Incorrect. LVM device paths are persistent.

A
The filesystem type is incorrectly specified as ext4 in fstab
Why wrong: Incorrect. The filesystem was created as ext4, so the type is correct.
B
The mount point /var/www/html does not exist after reboot
Why wrong: Incorrect. /var/www/html is a standard directory that exists.
C
The device path /dev/vg_data/lv_web is not persistent across reboots
Why wrong: Incorrect. LVM device paths are persistent.
D
The logical volume is not activated at boot because the volume group is not set to auto-activate
Correct. If the VG is not auto-activated, the LV device is not available, causing mount to fail at boot.