LFCS Multiple Select — 50 Questions

Question 1

A Linux administrator wants to restrict user 'alice' to only be able to use the system for non-interactive tasks (e.g., running cron jobs and receiving mail) but not allow her to log in via SSH or console. Which TWO actions would achieve this goal? (Choose two.)

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

Accepted Answer

Set alice's login shell to /sbin/nologin in /etc/passwd.. Sets alice's shell to /sbin/nologin, which prevents interactive logins (console, SSH, etc.) but still allows non-interactive tasks like cron jobs and mail delivery because those do not require a login shell. Option C adds alice to the DenyUsers directive in sshd_config, which blocks all SSH access regardless of authentication method (password or key). Together, these two measures ensure alice cannot log in interactively but can still run cron jobs and receive mail. Option A locks the password but does not prevent SSH key-based login. Option D gives root privileges. Option E blocks cron, which is not desired.

Answer

Lock alice's password with 'passwd -l alice'.

Answer

Change alice's UID to 0.

Answer

Add alice to /etc/cron.deny.

Question 2

An administrator needs to grant a user named 'john' the ability to switch to any other user without a password. Which TWO of the following steps are required to achieve this?

Accepted Answer

Add 'john' to the 'wheel' group and configure /etc/pam.d/su to use pam_wheel.so with the 'trust' option.. Adding 'john' to the 'wheel' group and configuring /etc/pam.d/su with pam_wheel.so and the 'trust' option allows members of the 'wheel' group to switch to any user via su without being prompted for a password. The 'trust' modifier in PAM bypasses the password authentication for users in the specified group, effectively granting passwordless su access.

Answer

Set the suid bit on /bin/su.

Answer

Run 'usermod -L john'.

Answer

Add 'john' to the 'root' group.

Question 3

Which THREE of the following are valid methods to temporarily switch to a different user account without logging out entirely? (Choose three.)

Accepted Answer

sudo -u username -s. Options A, B, and E are correct. `sudo -u username -s` launches a shell as the specified user. `su - username` starts a login shell as that user. `runuser -l username -c 'bash'` runs a command as another user (common in scripts). Option C (`newgrp groupname`) changes the group, not the user. Option D (`login username`) requires a full login, which logs out the current session.

Answer

newgrp groupname

Answer

login username

Question 4

A system administrator needs to check the firewall rules on a Linux server using firewalld. Which two commands can be used to list the current rules? (Choose two.)

Accepted Answer

firewall-cmd --list-all-zones. `firewall-cmd --list-all-zones` displays the firewall rules for all zones configured in firewalld, showing services, ports, and rules per zone. Option E is correct because `firewall-cmd --list-all` lists the rules for the default zone, providing a concise view of active firewall configuration. Both commands are native to firewalld and directly query its runtime and permanent rules via D-Bus.

Answer

systemctl status firewalld

Answer

iptables -S

Answer

iptables -L

Question 5

Which TWO commands can be used to display the contents of a text file that has been compressed with gzip without decompressing it to disk?

Accepted Answer

zcat file.gz. `zcat` is a standard utility that reads gzip-compressed files and decompresses the output to stdout, allowing you to view the contents without writing a decompressed file to disk. It is functionally equivalent to `gunzip -c` and is commonly used for inspecting compressed log files or text data.

Answer

xzcat file.gz

Answer

gzip -l file.gz

Answer

bzcat file.gz

Question 6

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 7

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 8

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 9

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 10

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 11

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

Question 12

Which THREE commands can show the current system time and date?

Accepted Answer

timedatectl. B is correct because `timedatectl` is the primary command in systemd-based Linux distributions (e.g., RHEL 7+, Ubuntu 16.04+) for querying and configuring system time, date, time zone, and NTP synchronization. It displays the current local time, UTC time, RTC time, and time zone status in a structured output.

Answer

time

Answer

ntpdate

Question 13

Which THREE of the following statements about Linux file permissions are correct?

Accepted Answer

The command 'chmod 400 secret.txt' sets read-only permission for the owner only.. The numeric permission mode 400 corresponds to read (4) for the owner, with no permissions for the group or others (0 and 0). This sets the file's permissions to r--------, meaning only the owner can read the file, and no one can write or execute it.

Answer

The command 'chmod a+w file' removes write permission for all.

Answer

The command 'chmod 644 file' sets permissions to rw-rw-rw-.

Question 14

Which TWO methods can be used to set a static IPv4 address on a CentOS 7 system? (Choose two.)

Accepted Answer

Use the nmtui utility. Nmtui is a text-based user interface for NetworkManager, which is the default networking service on CentOS 7. It allows you to interactively configure network interfaces, including setting a static IPv4 address, without needing to manually edit configuration files. Option E is correct because the ifcfg-eth0 file in /etc/sysconfig/network-scripts is the traditional, direct configuration method for network interfaces on CentOS 7, where you can set BOOTPROTO=static and define IPADDR, PREFIX, and GATEWAY.

Answer

Run the command 'systemctl set-static-ip eth0 192.168.1.100/24'

Answer

Use 'ip addr add 192.168.1.100/24 dev eth0'

Answer

Edit the /etc/network/interfaces file

Question 15

Which THREE conditions can cause an 'RTNETLINK answers: File exists' error when adding a static route?

Accepted Answer

The route exists with a different metric but same destination and netmask.. The Linux kernel's routing table uses the destination and netmask as a unique key for route entries. When adding a route with 'ip route add', if a route already exists with the same destination and netmask but a different metric, the kernel returns 'RTNETLINK answers: File exists' because the metric is not part of the uniqueness check — only the destination prefix and netmask are considered. The metric is a per-route property that does not disambiguate routes in the FIB (Forwarding Information Base).

Answer

The gateway is unreachable.

Answer

The interface is down.

Question 16

Which two commands produce output that includes the current runlevel or target? (Choose two.)

Accepted Answer

runlevel. The `runlevel` command displays the previous and current runlevel from the `/var/run/utmp` file, making it a direct way to see the current runlevel. The `who -r` command reads the same utmp file and prints the current runlevel along with the time of the last runlevel change, so both commands produce output that includes the current runlevel or target.

Answer

systemctl list-units --type=target

Answer

systemctl show-environment

Answer

systemctl get-default

Question 17

A system administrator needs to identify all available block devices on a Linux server. Which two commands can be used to accomplish this? (Choose two.)

Accepted Answer

lsblk. The `lsblk` command lists all available block devices (e.g., disks, partitions, LVM volumes) by reading the sysfs filesystem, providing a tree-like view of device hierarchy. The `fdisk -l` command displays the partition table for all block devices, showing detailed information about disk geometry and partitions. Both commands are standard tools for identifying block devices on a Linux system.

Answer

blkid

Answer

mount

Answer

df -h

Question 18

Which TWO commands can be used to check the status of a service?

Accepted Answer

service status. The `service` command is a legacy SysV init wrapper that can query the status of a service by calling the appropriate init script with the `status` argument. It remains available on many Linux distributions for backward compatibility, making it a valid tool to check service status.

Answer

systemd-analyze

Answer

start stop restart

Answer

initctl status

Question 19

Which TWO configuration files are commonly used to set DNS resolver settings on a Linux system?

Accepted Answer

/etc/nsswitch.conf. /etc/nsswitch.conf controls the order of name resolution sources (e.g., files, dns, mdns) via the 'hosts' database line. Option E is correct because /etc/resolv.conf directly specifies the DNS resolver settings, including nameserver IP addresses, search domains, and options, as defined by RFC 1035.

Answer

/etc/hostname

Answer

/etc/sysconfig/network

Answer

/etc/hosts

Question 20

Which THREE are built-in chains in the iptables filter table? (Choose three.)

Accepted Answer

INPUT. The filter table in iptables is used for packet filtering decisions based on IP addresses, ports, and protocols. Its built-in chains are INPUT (for packets destined for the local system), OUTPUT (for packets originating from the local system), and FORWARD (for packets routed through the system). These three chains allow you to control traffic at different points in the packet flow.

Answer

POSTROUTING

Answer

PREROUTING