LFCS Networking Practice Question
A server has two network interfaces: eth0 (10.0.1.10/24, gateway 10.0.1.1) and eth1 (192.168.1.10/24, no gateway). Both are up. The default gateway is set to 10.0.1.1. A ping to 8.8.8.8 fails, but ping to 10.0.1.1 succeeds. What is the most likely cause?
⚠ Common exam trap
The trap here is that candidates may incorrectly blame eth1's missing gateway (option A) instead of recognizing that the default route via eth0 is the sole path to external networks, and its absence is the real issue.
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
✓
The default route is missing or pointing to an incorrect gateway
Although the default gateway is set to 10.0.1.1, the default route may not be present in the routing table if it was not properly added or was later removed. The lack of a default route would allow pings to the local gateway (10.0.1.1) to succeed, but any attempt to reach an external IP like 8.8.8.8 would fail because the system does not know where to send the packets. Thus, the most likely cause is a missing or incorrectly configured default route.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
eth1 has no gateway configured
Why it's wrong here
eth1 is on a private subnet and does not need a gateway for external access.
- ✓
The default route is missing or pointing to an incorrect gateway
Why this is correct
Even though the gateway is reachable, the default route may be missing or misconfigured.
- ✗
DNS resolution is failing
Why it's wrong here
Ping uses IP addresses, not DNS.
- ✗
eth0 is down
Why it's wrong here
If eth0 were down, ping to 10.0.1.1 would fail.
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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.