LPIC-2 Network Client Management Practice Question
A company has a Linux client running Ubuntu 20.04 that is used by multiple developers. The client has two network interfaces: eth0 (connected to the corporate network with DHCP) and eth1 (connected to a test lab with static IP 192.168.100.10/24). The client needs to access both the internet (via eth0) and the lab network (192.168.100.0/24). The default gateway is 10.0.0.1 on eth0. The lab network has a server at 192.168.100.50 that provides DHCP for the lab devices, but the client's eth1 is statically configured. Recently, the client cannot reach the lab server at 192.168.100.50. The administrator checks the routing table and sees:
Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.0.0.1 0.0.0.0 UG 100 0 0 eth0 10.0.0.0 0.0.0.0 255.255.255.0 U 100 0 0 eth0 192.168.100.0 0.0.0.0 255.255.255.0 U 100 0 0 eth1
The administrator can ping 192.168.100.50 from the client. However, the lab server cannot ping the client. What is the most likely cause?
⚠ Common exam trap
A common mix-up: candidates assume a successful ping from client to server implies full bidirectional connectivity, but they overlook that firewalls often block inbound ICMP while permitting outbound, leading to a one-way communication 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 client's firewall is blocking incoming ICMP echo requests.
The client can ping the lab server (192.168.100.50), proving that outbound traffic from the client to the lab network works correctly. However, the lab server cannot ping the client, which indicates that either the return traffic is blocked or the client does not have a route back to the server. Since the client's routing table shows a direct route to 192.168.100.0/24 via eth1, the issue is not a missing route; instead, the most likely cause is that the client's firewall (e.g., iptables or ufw) is blocking incoming ICMP Echo Requests (ping) on eth1, while allowing outbound traffic.
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 lab server's default gateway is misconfigured.
Why it's wrong here
The lab server's default gateway does not affect direct communication within the same subnet.
- ✓
The client's firewall is blocking incoming ICMP echo requests.
Why this is correct
The client can initiate traffic but may block incoming connections, preventing the server from pinging back.
- ✗
The client has no route to the lab subnet.
Why it's wrong here
The routing table shows a route to 192.168.100.0/24 via eth1.
- ✗
The client's default gateway is misconfigured.
Why it's wrong here
The default gateway is correctly set to 10.0.0.1 for internet access; lab traffic is local.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.