LFCS Practice Test 12 — 15 Questions

Question 1

A junior administrator needs to mount an ISO image located at /opt/install.iso to the /mnt/iso directory to access its contents. Which command accomplishes this?

Accepted Answer

mount -o loop /opt/install.iso /mnt/iso. Mounting an ISO file requires the loop option so that the kernel treats the file as a block device. The command mount -o loop /opt/install.iso /mnt/iso creates a loop device automatically and mounts the ISO9660 filesystem, making the contents accessible. This is the standard method for accessing ISO images without burning them.

Answer

mount --bind /opt/install.iso /mnt/iso

Answer

losetup /dev/loop0 /opt/install.iso && mount /dev/loop0 /mnt/iso

Answer

mount -t iso9660 /opt/install.iso /mnt/iso

Question 2

A Linux server uses LVM. The volume group vg_data has 10 GB of free extents. The logical volume /dev/vg_data/lv_app is 20 GB and must be increased by 5 GB while it is mounted and actively used by an application. Which command sequence correctly extends the logical volume and then grows the ext4 filesystem online?

Accepted Answer

lvextend -L +5G /dev/vg_data/lv_app && resize2fs /dev/vg_data/lv_app. To extend an ext4 filesystem on LVM online, you first increase the logical volume with lvextend, then expand the filesystem with resize2fs. ext4 supports online growth, so the application can continue running. Using xfs_growfs on ext4 or running a filesystem check instead of resize2fs will not achieve the desired result.

Answer

lvextend -L +5G /dev/vg_data/lv_app && xfs_growfs /dev/vg_data/lv_app

Answer

lvresize -L +5G /dev/vg_data/lv_app && resize2fs /dev/vg_data/lv_app

Answer

lvextend -L 25G /dev/vg_data/lv_app && e2fsck -f /dev/vg_data/lv_app

Question 3

An administrator has a volume group vg_data with 50 GB of free extents. The logical volume /dev/vg_data/lv_archive is 200 GB and must grow to 350 GB. The administrator runs lvextend -L +150G /dev/vg_data/lv_archive and it fails. Which is the most likely cause?

Accepted Answer

The volume group does not have enough free extents to satisfy the 150 GB request.. lvextend allocates physical extents from the volume group's free pool. With only 50 GB free, a 150 GB growth request cannot be met, so the command exits with an error before touching the logical volume. The fix is to add capacity to vg_data, for example by creating a physical volume on a new disk and running vgextend, then repeating the lvextend.

Answer

The logical volume is formatted with XFS, which cannot be extended with lvextend.

Answer

The +150G syntax is invalid and should be --size 150G instead.

Answer

The filesystem must be unmounted before any logical volume can be extended.

Question 4

An administrator is configuring an NFS server and wants to export /srv/data to a specific client, 192.168.10.25, with read-write access, while ensuring that the client's root user is mapped to the anonymous user for security. Which entry should be placed in /etc/exports?

Accepted Answer

/srv/data 192.168.10.25(rw,root_squash). The correct export entry must specify the exact client, grant read-write access, and enable root squashing. The entry /srv/data 192.168.10.25(rw,root_squash) accomplishes all three requirements. root_squash is the default, but explicitly including it ensures the security policy is applied even if defaults change.

Answer

/srv/data 192.168.10.25(rw,no_root_squash)

Answer

/srv/data *(rw,root_squash)

Answer

/srv/data 192.168.10.25(ro,root_squash)

Question 5

An administrator is preparing a new server that will use software RAID 1 for the root filesystem. The system has two identical 500 GB disks, /dev/sda and /dev/sdb. The administrator wants to create the RAID array and then place LVM on top of it. Which command correctly creates the RAID 1 array using the entire disks?

Accepted Answer

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb. Creating a RAID 1 array on whole disks requires mdadm --create with --level=1 and --raid-devices=2, followed by the device paths. RAID 1 provides mirroring for redundancy. Using --level=0 would create a stripe with no redundancy, and --assemble is only for activating existing arrays. The correct device paths are the whole disks, not partitions.

Answer

mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sda /dev/sdb

Answer

mdadm --assemble /dev/md0 /dev/sda /dev/sdb

Answer

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1

Question 6

A junior administrator needs to identify the UUID of the ext4 filesystem on /dev/nvme0n1p2 so it can be referenced in /etc/fstab instead of the device path. Which command displays that UUID?

Accepted Answer

blkid /dev/nvme0n1p2. blkid probes the device and reports the filesystem UUID stored in the ext4 superblock, which is exactly the value needed for an fstab entry like UUID=xxxx-... /data ext4 defaults 0 2. It works whether or not the filesystem is mounted. The other commands either display partition-table metadata or require mounting and still do not print the UUID.

Answer

lsblk -o NAME,SIZE,TYPE

Answer

fdisk -l /dev/nvme0n1p2

Answer

mount | grep nvme0n1p2

Question 7

A server uses LVM with volume group vg_data. The logical volume lv_app is mounted at /srv/app and is 200 GiB. The administrator adds a new 500 GiB disk, /dev/sdb, creates a physical volume on it, and extends vg_data with it. They then run lvextend -L +100G /dev/vg_data/lv_app. The filesystem is ext4. Which command must be run next to make the additional space usable without unmounting /srv/app?

Accepted Answer

resize2fs /dev/vg_data/lv_app. After extending the logical volume with lvextend, the ext4 filesystem must be grown to use the new space. resize2fs performs this online for ext4, keeping /srv/app mounted. xfs_growfs targets XFS, e2fsck checks but does not resize, and lvresize would further change the logical volume without touching the filesystem. The correct sequence is lvextend then resize2fs.

Answer

lvresize -L +100G /dev/vg_data/lv_app

Answer

e2fsck -f /dev/vg_data/lv_app

Answer

xfs_growfs /srv/app

Question 8

A junior administrator needs to create a symbolic link named /usr/local/bin/editor that points to /opt/tools/vim.bin. The link must be created without overwriting any existing file at the destination. Which command accomplishes this?

Accepted Answer

ln -s /opt/tools/vim.bin /usr/local/bin/editor. Creating a symbolic link is done with ln -s target linkname. Because the destination does not exist, no force flag is required and the command completes without overwriting anything. The hard-link variant lacks -s and would not produce a symbolic link, while the forced variant introduces overwrite risk that the scenario explicitly forbids.

Answer

ln /opt/tools/vim.bin /usr/local/bin/editor

Answer

ln -sf /opt/tools/vim.bin /usr/local/bin/editor

Answer

cp -s /opt/tools/vim.bin /usr/local/bin/editor

Question 9

A support engineer must copy the directory /srv/appdata, including every subdirectory, hidden file, and preserved permission bits and timestamps, to /backup/appdata on the same host. Which command accomplishes this?

Accepted Answer

cp -a /srv/appdata /backup/appdata. Archive-mode copy is the correct tool when a directory tree must be duplicated with metadata intact, since it combines recursion with preservation of permissions, ownership, timestamps, and symlink structure. Recursive-only copy drops metadata, relocation deletes the source, and a bare rsync invocation without archive or recursive flags will not descend into directories.

Answer

mv /srv/appdata /backup/appdata

Answer

rsync /srv/appdata /backup/appdata

Answer

cp -r /srv/appdata /backup/appdata

Question 10

An administrator runs `ls -l` and sees a file entry whose permission string begins with a lowercase `l`. What does this indicate about the entry?

Accepted Answer

It is a symbolic link whose target is resolved when the link is accessed.. The first character of the permission string encodes file type, and l specifically means symbolic link. Device nodes, regular files, and FIFOs each have their own distinct type character, so recognizing the type column is essential before choosing commands such as readlink, stat, or find -type l.

Answer

It is a named pipe used for inter-process communication.

Answer

It is a regular file that has the setuid bit enabled.

Answer

It is a block device node used for buffered disk access.

Question 11

A user needs to locate all regular files under /etc that are larger than 1 MB and have not been accessed in the last 30 days. Which command finds these files?

Accepted Answer

find /etc -type f -size +1M -atime +30. The find command is the correct tool for complex file searches based on metadata. The -type f option restricts to regular files, -size +1M selects files larger than 1 MB, and -atime +30 identifies files not accessed in over 30 days. Together, these criteria match the administrator's needs exactly.

Answer

find /etc -type f -size +1M -mtime +30

Answer

locate /etc -type f -size +1M -atime +30

Answer

find /etc -type f -size 1M -atime 30

Question 12

A system administrator needs to create a hard link named /home/user/report_hardlink to an existing file /data/reports/report.txt. Which command should be used?

Accepted Answer

ln /data/reports/report.txt /home/user/report_hardlink. The ln command creates hard links by default. Providing the existing file as the first argument and the new link name as the second creates a hard link. Hard links share the same inode and data, so changes to one are reflected in the other. They cannot span filesystems. The correct command simply uses ln with the target and link name.

Answer

ln -s /data/reports/report.txt /home/user/report_hardlink

Answer

ln -h /data/reports/report.txt /home/user/report_hardlink

Answer

link -s /data/reports/report.txt /home/user/report_hardlink

Question 13

An administrator is configuring a Linux server as a router. The server has two interfaces: eth0 (192.168.10.1/24) connected to the internal LAN and eth1 (203.0.113.2/24) connected to the internet. After enabling IP forwarding, internal clients still cannot reach external websites. Which command is required to allow the internal subnet to be translated to the external interface?

Accepted Answer

iptables -t nat -A POSTROUTING -s 192.168.10.0/24 -o eth1 -j MASQUERADE. For internal clients to reach the internet through a Linux router, their private source addresses must be translated to the router's public address. The correct rule uses the nat table's POSTROUTING chain with MASQUERADE on the outbound interface, enabling source NAT for the internal subnet.

Answer

iptables -A FORWARD -s 192.168.10.0/24 -o eth1 -j ACCEPT

Answer

iptables -t nat -A PREROUTING -s 192.168.10.0/24 -o eth1 -j MASQUERADE

Answer

iptables -t nat -A POSTROUTING -d 192.168.10.0/24 -i eth1 -j SNAT --to-source 203.0.113.2

Question 14

An administrator is diagnosing disk space and wants to see the total size of the /var/log directory and all its contents in human-readable units, without listing every individual file. Which command provides exactly this summary?

Accepted Answer

du -sh /var/log. The du -sh combination reports a single human-readable total for the specified directory tree, which is precisely the summary needed. The other commands either report filesystem-level capacity, list individual entries, or enumerate every file, none of which deliver a concise total for /var/log.

Answer

du -ah /var/log

Answer

ls -lh /var/log

Answer

df -h /var/log

Question 15

A system administrator needs to identify which processes are consuming the most CPU and memory on a Linux server. Which TWO commands can provide a real-time, interactive view of process resource usage? (Choose two.)

Accepted Answer

top. top and htop are interactive, real-time process viewers that show CPU and memory usage per process. top is universally available, while htop offers enhanced usability. The other commands provide snapshots or system-wide statistics without per-process, real-time interactivity, so they do not meet the requirement.

Answer

vmstat 1

Answer

ps aux --sort=-%cpu

Answer

iostat -x 1