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LFCS Networking Practice Question

Exhibit

Refer to the exhibit.

# ip route show
10.0.1.0/24 dev eth0 proto kernel scope link src 10.0.1.10
10.0.2.0/24 dev eth1 proto kernel scope link src 10.0.2.10
default via 10.0.1.1 dev eth0

A host with this routing table can ping 10.0.2.1 but cannot ping 8.8.8.8. What is the most likely cause?

⚠ Common exam trap

Candidates often assume a missing default route is the only cause for internet unreachability, but the question explicitly states the routing table includes a default route, shifting the focus to the gateway's own connectivity or upstream routing failure.

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 gateway 10.0.1.1 does not have internet connectivity

The host can ping 10.0.2.1, which is on the directly connected 10.0.2.0/24 network, confirming that the local interface and link-layer are functional. However, it cannot ping 8.8.8.8, a public internet address. The routing table shows a default route via 10.0.1.1, so the host will forward the packet to that gateway. Since the host has a default route, the most likely cause is that the gateway 10.0.1.1 itself lacks internet connectivity (e.g., no upstream route, NAT misconfiguration, or ISP outage), preventing the packet from reaching 8.8.8.8.

Answer analysis

Option-by-option breakdown

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

  • The default route is missing

    Why it's wrong here

    The table shows a default route via 10.0.1.1.

  • The default gateway 10.0.1.1 does not have internet connectivity

    Why this is correct

    Even though the host can reach the gateway, the gateway itself may not have a path to the internet.

  • The host has no route to 10.0.2.0/24

    Why it's wrong here

    The table shows a direct route to 10.0.2.0/24 via eth1.

  • The host has no route to 10.0.1.1

    Why it's wrong here

    The host has a direct route to 10.0.1.0/24, so it can reach 10.0.1.1.

Visual reference

Inside (Private) PC-A 10.0.0.1 PC-B 10.0.0.2 NAT Router Outside (Public) 203.0.113.1 Inside Global Server PAT: many private IPs share one public IP via unique port numbers

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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.