The answer is using nmcli connection add and editing the /etc/network/interfaces file. The nmcli command is part of NetworkManager, a modern dynamic network control and configuration system that manages devices and connections via the command line, making it a valid method for both temporary and persistent configuration. The /etc/network/interfaces file, by contrast, is the traditional static configuration method used by the ifup/ifdown system on Debian-based distributions, where you define IP addresses, netmasks, and gateways directly. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your understanding of the two major configuration paradigms: the legacy file-based approach versus the newer NetworkManager toolset. A common trap is assuming only one method is valid, but the exam expects you to recognize that both coexist in modern distributions. Memory tip: think “nmcli for the new, interfaces for the old” — both are valid, just different eras.
LFCS Networking Practice Question
This LFCS practice question tests your understanding of networking. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO are valid methods to configure a network interface on a Linux system?
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
Option C is correct because /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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Related concept
Read the scenario before looking for a memorised answer.
✓
Using nmcli connection add
Why this is correct
nmcli is the command-line tool for NetworkManager.
Related concept
Read the scenario before looking for a memorised answer.
✗
Editing /etc/sysconfig/network
Why it's wrong here
This file contains hostname and global settings, not interface configuration.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates 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.
Detailed technical explanation
How to think about this question
The /etc/network/interfaces file uses a stanza-based syntax (e.g., 'auto eth0', 'iface eth0 inet static') that is processed by the ifup command, which calls helper scripts like /etc/network/if-pre-up.d/ and /etc/network/if-up.d/ for advanced options. In contrast, nmcli is part of NetworkManager, which can manage interfaces independently of the legacy ifupdown system, and on systems with both, conflicts can arise if both methods are used simultaneously. Real-world scenarios often involve hybrid environments where administrators must choose between the traditional static file approach and dynamic management via NetworkManager.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking — This question tests Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Editing /etc/network/interfaces — Option C is correct because /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.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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