LFCS Practice Exam 2 — 20 Questions

Question 1

A database server is running out of space in its /var/lib/mysql directory. The system admin wants to add a new 100GB disk to increase storage. Which of the following steps should be performed to mount the new filesystem at /var/lib/mysql without data loss?

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

Accepted Answer

Partition the disk, create a filesystem, mount it at a temporary mount point, copy existing data from /var/lib/mysql to the new filesystem, unmount /var/lib/mysql (if it's a mount), mount the new filesystem at /var/lib/mysql, and update /etc/fstab.. It ensures no data loss by first copying existing data to the new filesystem mounted at a temporary point, then unmounting the old mount (if any) and remounting the new filesystem at /var/lib/mysql. This preserves the existing database files and allows the new disk to be used without disrupting the directory structure. The /etc/fstab update ensures the mount persists across reboots.

Answer

Add the new disk as an LVM physical volume, extend the volume group, extend the logical volume containing /var/lib/mysql, and then resize the filesystem.

Answer

Partition the disk, create a filesystem, add an entry in /etc/fstab, and reboot the server.

Answer

Partition the disk, create a filesystem, mount it directly to /var/lib/mysql, and then move the existing data into place.

Question 2

Which THREE of the following are valid methods to mount an NFS filesystem on a client?

Accepted Answer

mount -o hard,intr server:/export /mnt. The `mount` command with `-o hard,intr` specifies NFS-specific mount options: `hard` ensures that NFS operations retry indefinitely until the server responds, and `intr` allows signals to interrupt a hung NFS operation. The command `mount -o hard,intr server:/export /mnt` uses the default NFS version (typically NFSv3) and is a valid method to mount an NFS filesystem on a client.

Answer

echo 'server:/export /mnt nfs defaults 0 0' >> /etc/fstab && mount -a

Answer

mount -t cifs server:/share /mnt

Question 3

A system administrator needs to securely transfer files between two Linux servers using port 22. The administrator uses the following command: 'scp file.txt user@remote:/tmp/'. The transfer fails with the error 'Permission denied (publickey)'. What is the most likely cause?

Accepted Answer

The client's public key is not in the remote user's authorized_keys file.. The error 'Permission denied (publickey)' indicates that the SSH key-based authentication failed. SCP uses SSH for transport, and by default, SSH on the remote server checks the client's public key against the remote user's ~/.ssh/authorized_keys file. If the client's public key is not listed there, the SSH server rejects the connection, causing the SCP transfer to fail.

Answer

The remote server does not have SSH installed.

Answer

The SSH service is not running on the remote server.

Answer

The remote server's firewall is blocking port 22.

Question 4

An administrator wants to change the primary group of user 'jane' from 'staff' to 'developers'. Which command accomplishes this?

Accepted Answer

usermod -g developers jane. The `usermod -g` command changes the primary group of a user. The `-g` option specifies the new primary group (by name or GID), and the user's existing primary group is replaced. This directly accomplishes the administrator's goal of changing jane's primary group from 'staff' to 'developers'.

Answer

usermod -G developers jane

Answer

groupmod -g developers jane

Answer

chgrp developers jane

Question 5

An administrator wants to extend a logical volume named 'lv_data' in volume group 'vg_data' by 5GB. The volume group has free physical extents. Which command should be used?

Accepted Answer

lvextend -L +5G /dev/vg_data/lv_data. The correct command to extend a logical volume is `lvextend`. Option B uses the correct syntax with the `-L +5G` flag, which adds 5GB to the existing logical volume `/dev/vg_data/lv_data`. The volume group `vg_data` has free physical extents, so the extension can proceed without needing to add new physical volumes.

Answer

pvextend -L +5G /dev/vg_data/lv_data

Answer

lvresize -L +5G /dev/vg_data/lv_data

Answer

lvextend -L 5G /dev/vg_data/lv_data

Question 6

Based on the exhibit, what is the correct interpretation?

Accepted Answer

The service is running but the unit file has been modified recently and needs reloading. The 'daemon-reload' notice in the systemctl status output indicates that the unit file has been modified on disk but systemd has not yet reloaded its configuration. Running 'systemctl daemon-reload' will re-read the unit files and apply the changes, which is why option C is correct.

Answer

The service is inactive

Answer

The configuration file is corrupt

Answer

The service is failing

Question 7

A server has two network interfaces: eth0 (192.168.1.10/24) and eth1 (10.0.0.10/24). The default gateway is 192.168.1.1. The administrator wants traffic to 10.0.1.0/24 to go through eth1's gateway 10.0.0.1. Which command adds this route?

Accepted Answer

Both B and C are correct. Both B and C are valid `ip route add` syntax variations that achieve the same result: adding a route to 10.0.1.0/24 via gateway 10.0.0.1 on interface eth1. The `ip route` command accepts the `via` and `dev` keywords in either order, making both B and C syntactically correct. Option D uses the legacy `route` command with improper syntax (missing `dev` keyword before the interface name), which would fail or produce unexpected behavior.

Answer

ip route add 10.0.1.0/24 via 10.0.0.1 dev eth1

Answer

ip route add 10.0.1.0/24 dev eth1 via 10.0.0.1

Answer

route add -net 10.0.1.0 netmask 255.255.255.0 gw 10.0.0.1 eth1

Question 8

Based on the exhibit, what is the most likely cause of the nginx failure and the appropriate first step to resolve it?

Accepted Answer

Check which process is listening on port 80 with 'ss -tlnp' and stop that process.. The error 'Address already in use' indicates port 80 is occupied by another process. Checking with 'ss -tlnp' or 'lsof' identifies the offending process. Option A is incorrect as restarting would fail again. Option C is incorrect because worker_connections affects performance, not binding. Option D is incorrect because MaxClients is an Apache directive, not nginx.

Answer

Restart the nginx service.

Answer

Increase the worker_connections in nginx.conf.

Answer

Reduce the MaxClients parameter in nginx.conf.

Question 9

An administrator configures a systemd service with Restart=on-failure and RestartSec=10. What happens if the service exits with a non-zero exit code?

Accepted Answer

It waits 10 seconds before restarting. When Restart=on-failure is set, systemd only restarts the service if it exits with a non-zero exit code or is terminated by a signal (excluding SIGHUP, SIGINT, SIGTERM, and SIGPIPE). The RestartSec=10 directive then introduces a 10-second delay before the restart attempt, preventing rapid restart loops and giving the system time to stabilize.

Answer

It restarts immediately

Answer

It retries infinitely regardless of exit code

Answer

It does not restart

Question 10

A system administrator notices that a web server is not reachable from the internet but is reachable from the internal network. The server's IP is 10.0.1.10/24, and the gateway is 10.0.1.1. Which command should be used to verify the default gateway configuration?

Accepted Answer

ip route show. The `ip route show` command displays the kernel routing table, including the default gateway entry. Since the server is reachable internally but not from the internet, a missing or incorrect default gateway is the likely cause. This command directly verifies whether a default route (e.g., via 10.0.1.1) is present.

Answer

arp -a

Answer

ip addr show

Answer

ss -tln

Question 11

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 12

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 13

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 14

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 15

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 16

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 17

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 18

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 19

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 20

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