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LFCS Networking Practice Question

Which TWO are valid methods to configure a network interface on a Linux system?

⚠ Common exam trap

Candidates often confuse global network configuration files (like /etc/sysconfig/network) with per-interface configuration files, or mistake sysctl for a tool that can set interface IP addresses, when it only modifies kernel parameters unrelated to interface addressing.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Editing /etc/network/interfaces

/etc/network/interfaces is the traditional configuration file used by the ifup/ifdown system on Debian-based distributions to define network interfaces, including IP addresses, netmasks, and gateways. This file is parsed by the ifup command to bring interfaces up with the specified settings, making it a valid method for persistent network configuration.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Using sysctl to set net.ipv4.conf.eth0.forwarding

    Why it's wrong here

    sysctl is for kernel parameters, not for configuring interface IP addresses.

  • Using systemctl enable network.service

    Why it's wrong here

    This enables the network service but does not configure interfaces.

  • Editing /etc/network/interfaces

    Why this is correct

    This file is used by ifupdown on Debian/Ubuntu systems.

  • Using nmcli connection add

    Why this is correct

    nmcli is the command-line tool for NetworkManager.

  • Editing /etc/sysconfig/network

    Why it's wrong here

    This file contains hostname and global settings, not interface configuration.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.