LFCS Practice Questions

Question 1

After deleting user 'alice', the system administrator wants to also remove the home directory and mail spool. Which command should be used?

Accepted Answer

userdel -r alice. The correct option is B, userdel -r alice. The -r flag removes the user's home directory and mail spool, along with the user account. This is the standard flag for removing user data along with the account.

Answer

userdel -Z alice

Answer

userdel -f alice

Answer

userdel --remove alice

Question 2

Which TWO commands can be used to resolve a hostname to an IP address?

Accepted Answer

host. The `host` command is a simple DNS lookup utility that queries DNS servers to resolve a hostname to an IP address. It directly performs forward DNS resolution using the system's configured resolvers and returns the A or AAAA record for the given name.

Answer

traceroute

Answer

ping

Answer

ifconfig

Question 3

A system administrator is managing a RHEL 8 server that requires a static IP address on interface ens192. The administrator modifies /etc/sysconfig/network-scripts/ifcfg-ens192 to set BOOTPROTO=static, IPADDR=192.168.1.100, PREFIX=24, GATEWAY=192.168.1.1, and DNS1=8.8.8.8. After saving, the administrator runs 'systemctl restart NetworkManager'. The interface obtains the correct static IP and network connectivity works. However, after a reboot of the server, the interface fails to come up with the static IP and instead obtains an IP via DHCP from the local network. The administrator verifies that the DHCP server is active and that the physical connection is good. What is the most likely cause of the issue?

Accepted Answer

The ONBOOT parameter is set to no or missing in the configuration file.. The ONBOOT parameter controls whether the interface is activated at system boot. If set to 'no' or missing entirely, NetworkManager will not bring up the interface automatically after a reboot, causing it to fall back to DHCP if a DHCP client is active. Setting BOOTPROTO=static and IPADDR correctly only takes effect when ONBOOT=yes is present.

Answer

The kernel parameter nomodeset is set in /etc/default/grub.

Answer

The firewall is blocking the static IP assignment.

Answer

The network service is not enabled to start at boot.

Question 4

Which TWO commands can be used to display listening TCP ports on a Linux system?

Accepted Answer

ss -tln. The `ss -tln` command displays listening TCP sockets by using the `-t` flag for TCP, `-l` for listening sockets, and `-n` to show numeric addresses and ports without resolving service names. It reads socket information directly from the kernel's netlink interface, making it the modern replacement for netstat on Linux systems.

Answer

nmap -sT localhost

Answer

iptables -L

Answer

lsof -i TCP

Question 5

A system administrator needs to list all files in the current directory, including hidden files, in a long listing format sorted by modification time (oldest first). Which command achieves this?

Accepted Answer

ls -lart. `ls -lart` combines the `-l` (long listing), `-a` (include hidden files starting with dot), `-r` (reverse order), and `-t` (sort by modification time, newest first). The reverse flag flips the sort to oldest first, meeting the requirement exactly.

Answer

ls -lihrt

Answer

ls -lat

Answer

ls -lrt

Question 6

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 7

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 8

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 9

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 10

Which TWO of the following commands can be used to check and repair an ext4 filesystem?

Accepted Answer

fsck.ext4 /dev/sdb1. Option A, fsck.ext4 /dev/sdb1, is correct because fsck.ext4 is the ext4-specific front-end of the fsck utility, which checks and repairs ext4 filesystems on the specified block device. Option D, e2fsck /dev/sdb1, is also correct because e2fsck is the underlying ext2/ext3/ext4 filesystem checker that fsck.ext4 invokes, and it can both verify and repair ext4 filesystems. Option B, xfs_repair, is wrong because it is the repair tool for XFS filesystems, not ext4. Option C, mkfs.ext4, is wrong because it creates (formats) a new ext4 filesystem rather than checking or repairing an existing one. Option E, btrfs check, is wrong because it is used to check Btrfs filesystems, not ext4.

Answer

xfs_repair /dev/sdb1

Answer

mkfs.ext4 /dev/sdb1

Answer

btrfs check /dev/sdb1

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

A system administrator needs to ensure that a Linux server can communicate with other hosts on the same subnet. Which command should be used to verify the IP address and netmask configuration?

Accepted Answer

ip addr show. The `ip addr show` command is the modern, recommended tool in Linux for viewing IP addresses and netmasks (prefix lengths) assigned to network interfaces. It directly displays the configuration needed to verify subnet communication, unlike legacy tools that may not show the netmask clearly or mix routing information.

Answer

netstat -rn

Answer

route -n

Answer

ifconfig

Question 13

A user reports that they cannot reach a remote server by hostname but can reach it by IP address. Which configuration file is most likely misconfigured?

Accepted Answer

/etc/resolv.conf. The /etc/resolv.conf file configures the system's DNS resolver, specifying the nameservers to query for hostname-to-IP resolution. If a user can reach a server by IP but not by hostname, it indicates that DNS resolution is failing, which is most commonly due to a missing or incorrect nameserver entry in /etc/resolv.conf.

Answer

/etc/sysconfig/network

Answer

/etc/hosts

Answer

/etc/nsswitch.conf

Question 14

A system administrator needs to schedule a one-time task that will run at 2:30 AM on July 15. Which command should be used to create this job?

Accepted Answer

at 2:30 AM July 15. The at command is specifically designed for scheduling one-time tasks at a precise date and time. Using at 2:30 AM July 15 allows the administrator to queue a command that will execute once at that moment, fulfilling the requirement.

Answer

crontab -e

Answer

systemd-run --on-calendar="*-07-15 02:30:00"

Answer

batch

Question 15

An administrator needs to compress a directory named 'project' into a tarball with maximum compression using gzip. Which command is appropriate?

Accepted Answer

tar -czvf archive.tar.gz project. The `-z` flag tells tar to compress the archive using gzip. The `-c` flag creates a new archive, `-v` provides verbose output, and `-f` specifies the archive filename. The `.tar.gz` extension is the conventional extension for a gzip-compressed tarball. Although other tools like bzip2 or xz can achieve higher compression ratios, the question explicitly asks for using gzip.

Answer

tar -cjvf archive.tar.bz2 project

Answer

tar -cJvf archive.tar.xz project

Answer

tar -cvf archive.tar project

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