Quick Answer
The answer is `/etc/network/interfaces`. On Debian-based systems using the ifupdown suite, this file is the single source of truth for persistent network configuration, including the default gateway. The `gateway` directive is placed under a specific interface stanza (e.g., `iface eth0 inet static`) to ensure the route is automatically restored after a reboot, rather than being set temporarily with `ip route add`. For the LPIC-2 exam, this tests your understanding of legacy but still-critical Debian networking—a common trap is assuming `systemd-networkd` or `NetworkManager` handles this, but ifupdown ignores those entirely. Remember: if the system uses `ifup`/`ifdown` scripts, you must edit `/etc/network/interfaces`; a quick memory tip is "gateway goes in the stanza, not in a script."
This LPIC-2 practice question tests your understanding of advanced networking configuration. 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.
A system administrator notices that the default gateway is missing after a reboot. The network configuration uses ifup/ifdown scripts. Which file should be modified to ensure the default gateway is persistent?
/etc/resolv.conf
Why wrong: This file configures DNS, not default gateway.
/etc/network/routes
Why wrong: This file is not standard; static routes can be defined in /etc/network/interfaces.
/etc/sysconfig/network
Why wrong: This is used in Red Hat-based systems, not Debian.
/etc/network/interfaces
The 'gateway' directive in this file sets the default gateway persistently.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
/etc/network/interfaces
On Debian-based systems using ifup/ifdown scripts, persistent network configuration—including the default gateway—is defined in /etc/network/interfaces. The gateway is set with the 'gateway' directive under the appropriate interface stanza, ensuring it is applied automatically on boot. This file is the central configuration source for the ifupdown suite.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
/etc/resolv.conf
Why it's wrong here
This file configures DNS, not default gateway.
/etc/network/routes
Why it's wrong here
This file is not standard; static routes can be defined in /etc/network/interfaces.
/etc/sysconfig/network
Why it's wrong here
This is used in Red Hat-based systems, not Debian.
/etc/network/interfaces
Why this is correct
The 'gateway' directive in this file sets the default gateway persistently.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates familiar with Red Hat systems may incorrectly choose /etc/sysconfig/network, forgetting that the question explicitly specifies ifup/ifdown scripts, which are characteristic of Debian-based distributions.
Detailed technical explanation
The ifupdown suite reads /etc/network/interfaces and executes scripts in /etc/network/if-pre-up.d/ and /etc/network/if-up.d/ to apply configuration. The 'gateway' directive adds a default route via the 'route add default gw <ip>' command internally. A subtle behavior: if multiple interfaces have a 'gateway' directive, only the last one processed takes effect, which can cause unexpected routing after reboot.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the LPIC-2 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Advanced Networking Configuration — This question tests Advanced Networking Configuration — Read the scenario before looking for a memorised answer..
The correct answer is: /etc/network/interfaces — On Debian-based systems using ifup/ifdown scripts, persistent network configuration—including the default gateway—is defined in /etc/network/interfaces. The gateway is set with the 'gateway' directive under the appropriate interface stanza, ensuring it is applied automatically on boot. This file is the central configuration source for the ifupdown suite.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This LPIC-2 practice question is part of Courseiva's free LPI 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 LPIC-2 exam.
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