LFCS Practice Test 2 — 30 Questions

Question 1

After editing /etc/sysconfig/network-scripts/ifcfg-eth0, the network service fails to start. Which is the best command to investigate?

Accepted Answer

systemctl status NetworkManager. The best command to investigate why the network service fails to start after editing an interface configuration file is `systemctl status NetworkManager`, because it shows the current state, recent log entries, and any error messages from the NetworkManager service. Since NetworkManager is the default network service on modern RHEL/CentOS systems, checking its status directly reveals whether it failed to reload or start, and often includes the specific configuration error.

Answer

nmcli device status

Answer

journalctl -u NetworkManager

Answer

ip link show eth0

Question 2

Which THREE of the following actions require root privileges?

Accepted Answer

Changing another user's password. Changing another user's password (Option B) requires root privileges because the `passwd` command, when used to change another user's password, must write to `/etc/shadow`, which is owned by root and has permissions 000 (or 600) on most systems. Only root can modify this file directly or via the `passwd` command with a target username. Non-root users can only change their own password, which is handled by the `passwd` command's setuid bit, not by direct file access.

Answer

Changing your own login shell

Answer

Changing your own password

Question 3

A Linux server at a hosting provider uses a software RAID 5 array with three 2 TB disks (sda, sdb, sdc) configured as /dev/md0, hosting a large ext4 filesystem. The server experiences a performance degradation and I/O errors. The administrator checks /proc/mdstat and sees that /dev/sda is marked as failed. The remaining two disks are still active. The administrator has a spare disk /dev/sdd of the same size. The filesystem is sparse and can tolerate downtime. What is the most appropriate course of action to restore the array to a fully functional state with redundancy?

Accepted Answer

Run 'mdadm --manage /dev/md0 --fail /dev/sda --remove /dev/sda', then 'mdadm --manage /dev/md0 --add /dev/sdd'.. The proper procedure to replace a failed disk in a RAID 5 array is to first mark the failed disk as failed using '--fail', then remove it with '--remove', and finally add the new disk with '--add', which triggers an automatic rebuild. Option A is incorrect because recreating the array from scratch would destroy all existing data, requiring a backup restore, which is unnecessary when only one disk has failed. Option C is incorrect because simply adding the new disk without first removing the failed one will not allow the array to use the new disk; the array still recognizes the failed disk as part of the array and will not rebuild. Option D is incorrect because LVM is not a RAID solution and cannot directly manage or repair an existing MD RAID array; it would require recreating the storage stack and does not leverage the existing RAID metadata.

Answer

Recreate the RAID 5 array from scratch using all three healthy disks (sdb, sdc, sdd) and restore data from backup.

Answer

Run 'mdadm --manage /dev/md0 --add /dev/sdd' to directly add the new disk and let the array rebuild automatically.

Answer

Use LVM to mirror the two healthy disks and ignore the failed one, ensuring data redundancy.

Question 4

Which THREE statements about Linux network bonding modes are correct? (Choose three.)

Accepted Answer

Mode 0 (balance-rr) can cause out-of-order packet delivery.. Mode 0 (balance-rr) transmits packets in sequential order from the first available slave through the last, then starts over. This round-robin distribution can cause packets belonging to the same TCP session to take different physical paths, leading to out-of-order delivery at the receiver, which may trigger TCP retransmissions and degrade performance.

Answer

Mode 2 (balance-xor) distributes traffic based on packet type.

Answer

Modes 5 and 6 (balance-tlb and balance-alb) require IEEE 802.3ad switch support.

Question 5

After running 'chage -l bob', the output shows: 'Last password change: Apr 01, 2023', 'Password expires: May 31, 2023', 'Account expires: Jul 15, 2023'. What will happen on May 31, 2023?

Accepted Answer

Bob can still log in but will be forced to change his password.. On May 31, 2023, Bob's password expires. According to the PAM (Pluggable Authentication Modules) configuration and the `chage` command's behavior, a password expiration does not lock the account or disable the password; instead, it forces the user to change their password at the next login. The user can still authenticate with their current password, but upon successful authentication, the system will prompt them to set a new password before granting access to the shell.

Answer

Bob's account will be locked.

Answer

Bob's password will be disabled.

Answer

Bob will receive a warning message only.

Question 6

An administrator notices that the system clock is drifting significantly. To synchronize time using NTP, which command should be used to immediately sync with a server?

Accepted Answer

chronyd -q. `chronyd -q` sends a single NTP query to synchronize the system clock immediately and then exits, which is ideal for one-shot synchronization. This command is part of the `chrony` suite, the default NTP implementation on modern RHEL/CentOS 8+ and Ubuntu 18.04+ systems, and it respects the NTP protocol (RFC 5905) for accurate time adjustment.

Answer

ntpdate -u pool.ntp.org

Answer

ntpd -g

Answer

timedatectl set-ntp true

Question 7

A process is consuming 99% CPU and is unresponsive to normal shutdown requests. After running 'top', you see the PID is 1234. What is the most appropriate command to stop the process gracefully first?

Accepted Answer

kill -15 1234. Kill -15 1234. The SIGTERM signal (15) is the standard way to request a process terminate gracefully, allowing it to clean up resources, close files, and perform shutdown routines. This is the most appropriate first step before escalating to stronger signals, as it gives the process a chance to exit normally.

Answer

kill -19 1234

Answer

kill -2 1234

Answer

kill -9 1234

Question 8

A security policy requires that a user account 'temp_audit' be locked immediately without changing the password. Which command locks the account and prevents login?

Accepted Answer

usermod -L temp_audit. The `usermod -L` command locks a user account by placing an exclamation mark (!) at the beginning of the password hash in /etc/shadow, effectively disabling password-based authentication without altering the existing password. This satisfies the security policy requirement to immediately prevent login without changing the password.

Answer

userdel temp_audit

Answer

chage -E 0 temp_audit

Answer

passwd -u temp_audit

Question 9

A user reports that a script fails with 'Permission denied' when executed. The script has permissions -rw-r--r-- and is owned by the user. Which command should the user run to make the script executable for the owner only?

Accepted Answer

chmod u+x script.sh. The script currently has permissions `-rw-r--r--`, meaning the owner has read and write but not execute permission. The `chmod u+x` command adds the execute permission for the owner only, which is exactly what the user needs to run the script without affecting group or others.

Answer

chmod u+s script.sh

Answer

chown :users script.sh

Answer

chmod +x script.sh

Question 10

An administrator wants to ensure that a service is listening on TCP port 8080 and accessible from remote hosts. Which command will confirm that the service is listening on the correct interface?

Accepted Answer

ss -tlnp. The `ss -tlnp` command displays listening (`-l`) TCP (`-t`) sockets with numeric addresses (`-n`) and the associated process (`-p`), which directly confirms that a service is bound to TCP port 8080 on a specific interface (e.g., 0.0.0.0:8080 or 192.168.1.10:8080). This ensures the service is listening on the correct interface and is reachable from remote hosts.

Answer

iptables -L

Answer

netstat -i

Answer

ip addr

Question 11

A system administrator needs to mount an ext4 filesystem with the options 'noatime' and 'errors=remount-ro'. Which mount command is correct?

Accepted Answer

mount -o noatime,errors=remount-ro /dev/sda1 /mnt. The `mount -o noatime,errors=remount-ro /dev/sda1 /mnt` command uses a single `-o` flag with a comma-separated list of mount options, which is the proper syntax for specifying multiple options. The `noatime` option disables updating the access time on reads, and `errors=remount-ro` tells the kernel to remount the filesystem as read-only if an I/O error is encountered, both of which are valid ext4 mount options.

Answer

mount -o noatime,errors=remount /dev/sda1 /mnt

Answer

mount -o noatime -o errors=remount-ro /dev/sda1 /mnt

Answer

mount -o atime=no,errors=remount-ro /dev/sda1 /mnt

Question 12

Which THREE of the following statements about the user private group (UPG) scheme are true?

Accepted Answer

It is the default scheme in Red Hat-based distributions.. Options A, D, and E are true. A: It is the default scheme in Red Hat-based distributions. D: It ensures that new files have a default group of the user's private group. E: Each user is assigned a unique group with the same name as the username. B is false because umask 0027 gives group read permission, not denies it. C is false because the primary group is the user's private group, not a system group.

Answer

The umask 0027 ensures files created are NOT readable by the group.

Answer

The primary group of a user is a system group with GID less than 1000.

Question 13

Which command displays the UUID of all filesystems on the system?

Accepted Answer

lsblk -f. The `lsblk -f` command lists all block devices and includes the filesystem type and UUID for each filesystem, making it the correct choice for displaying UUIDs of all filesystems on the system. The `-f` option specifically adds filesystem information, including UUIDs, to the output.

Answer

blkid

Answer

df -h

Answer

fdisk -l

Question 14

A server has two network interfaces: eth0 (public IP 203.0.113.10/24) and eth1 (private IP 10.0.0.1/8). The default gateway is 203.0.113.1. The admin wants to ensure that traffic to the private subnet 10.0.0.0/8 goes via eth1. Which command correctly adds a static route?

Accepted Answer

ip route add 10.0.0.0/8 dev eth1. It adds a static route for the 10.0.0.0/8 network directly via the eth1 interface, which is the private interface with IP 10.0.0.1/8. The `ip route add` command with `dev eth1` specifies that traffic destined for the 10.0.0.0/8 subnet should be sent out through eth1, without needing a next-hop gateway since eth1 is directly connected to that subnet.

Answer

ip route add 10.0.0.1/8 dev eth1

Answer

ip route add 10.0.0.0/8 via 10.0.0.1 dev eth0

Answer

route add -net 10.0.0.0/8 eth1

Question 15

Order the steps to mount an ext4 filesystem from an external USB drive automatically at boot.

Accepted Answer

Identify the UUID using blkid, create the mount point directory, add an entry to /etc/fstab using the UUID with options defaults and dump/pass values, then run mount -a to test.. Using UUID in fstab ensures persistent mounting; testing with mount -a verifies no errors.

Answer

Plug in the USB drive, create the mount point, add an entry to /etc/fstab using the device name (e.g., /dev/sdb1), then reboot without testing.

Answer

Run mount -a first, then edit /etc/fstab to add the entry using UUID, and finally create the mount point.

Answer

Add an entry to /etc/fstab using the device name, manually mount with mount command, then create the mount point after mounting.

Question 16

Which command adds an existing user to a supplementary group without removing the user from other groups?

Accepted Answer

usermod -aG groupname username. The correct command is `usermod -aG groupname username`. The `-a` option (append) combined with `-G` (supplementary groups) adds the user to the specified group without affecting existing supplementary group memberships. Option A (`groupmod -a`) is incorrect because `groupmod` modifies group attributes, not user membership. Option B (`-A`) is not a valid `usermod` option. Option D (`-g`) changes the user's primary group, not supplementary groups.

Answer

groupmod -a username groupname

Answer

usermod -A groupname username

Answer

usermod -g groupname username

Question 17

A system administrator wants to limit the CPU usage of a service. Which systemd resource control directive should be used?

Accepted Answer

CPUAccounting=yes and CPUQuota. To limit CPU usage in systemd, you must first enable CPU accounting with `CPUAccounting=yes` to track CPU consumption, and then set `CPUQuota` to specify a maximum percentage of CPU time the service can use. Without `CPUAccounting=yes`, the `CPUQuota` directive is ignored by systemd, making the combination essential for enforcing a hard CPU limit.

Answer

CPUShares

Answer

CPUQuota

Answer

CPULimit

Question 18

Which THREE of the following commands can be used to view the contents of a compressed file named 'file.gz' without permanently decompressing it? (Choose exactly three.)

Accepted Answer

zmore file.gz. `zmore` is a utility that allows you to view the contents of a compressed file (such as `file.gz`) page by page without permanently decompressing it. It internally decompresses the file on the fly and pipes the output through `more`, making it ideal for inspecting large compressed files without modifying the original archive.

Answer

gzip file.gz

Answer

gunzip file.gz

Question 19

A user wants to view the contents of a compressed log file /var/log/syslog.2.gz without decompressing it first. Which command should they use?

Accepted Answer

zcat /var/log/syslog.2.gz. `zcat` is a utility that reads compressed files (typically gzip-compressed) and outputs their decompressed content to standard output without permanently decompressing the file. This allows the user to view the contents of `/var/log/syslog.2.gz` directly in the terminal.

Answer

gunzip /var/log/syslog.2.gz

Answer

cat /var/log/syslog.2.gz

Answer

less /var/log/syslog.2.gz

Question 20

Which THREE steps are required to create a new ext4 filesystem on /dev/sdc1 and ensure it is automatically mounted at /mnt/data at boot? (Choose three.)

Accepted Answer

mkfs.ext4 /dev/sdc1. B is correct because `mkfs.ext4 /dev/sdc1` creates a new ext4 filesystem on the specified partition. This is the fundamental step to format the device with the ext4 filesystem type, which is required before the partition can be mounted and used for data storage.

Answer

e2label /dev/sdc1 data

Answer

mount /dev/sdc1 /mnt/data