LFCS Practice Test 4 — 10 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