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.
You manage a Linux server that provides DHCP services to a small office network using the dhcpd daemon. The server has two network interfaces: eth0 (192.168.1.1/24) serving the internal network, and eth1 (192.168.0.1/24) connected to a DMZ. The DHCP server is configured to serve addresses only on eth0. Users on the internal network report that they are not receiving IP addresses. You check the DHCP server and find that the dhcpd service is running and listening on UDP port 67. From a client, you run tcpdump and see DHCPDISCOVER packets being sent, but no DHCPOFFER from the server. You also verify that no firewall rules are blocking DHCP traffic on either side. What is the most likely reason for the failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The dhcpd configuration file does not have a subnet declaration for the 192.168.1.0/24 network.
Option B is correct because the dhcpd daemon will only respond to DHCPDISCOVER packets on interfaces for which it has a matching subnet declaration in its configuration file (typically /etc/dhcp/dhcpd.conf). Without a subnet declaration for 192.168.1.0/24, dhcpd ignores all DHCP traffic on eth0, even though the service is running and listening on UDP port 67. The absence of DHCPOFFER packets despite seeing DHCPDISCOVERs confirms that the server is not processing the requests for that subnet.
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.
✗
The DHCP server's IP address is not in the same subnet as the clients.
Why it's wrong here
The server's IP is 192.168.1.1, which is in the same subnet, so this is not an issue.
✓
The dhcpd configuration file does not have a subnet declaration for the 192.168.1.0/24 network.
Why this is correct
Without a subnet declaration, the DHCP server does not know which pool to offer addresses from and will ignore broadcasts on that subnet.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The dhcpd service is not running.
Why it's wrong here
The stem says it is running.
✗
The network switch is blocking broadcast packets.
Why it's wrong here
The client can send DHCPDISCOVER, and broadcasts are generally allowed on a switch.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a running service with an open port (UDP 67) is sufficient to serve DHCP, but the dhcpd daemon requires explicit subnet declarations to process requests on each interface.
Detailed technical explanation
How to think about this question
The dhcpd daemon uses the subnet declaration to bind to a specific interface and define the address pool; without it, the server will not respond to DHCPDISCOVERs on that interface, even if the service is running. This behavior is defined in the ISC DHCP implementation, where the server matches incoming packets to subnet declarations based on the interface's IP address. In real-world scenarios, administrators often forget to add a subnet declaration for a new VLAN or interface, leading to silent failures that are hard to diagnose without checking the configuration file.
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: The dhcpd configuration file does not have a subnet declaration for the 192.168.1.0/24 network. — Option B is correct because the dhcpd daemon will only respond to DHCPDISCOVER packets on interfaces for which it has a matching subnet declaration in its configuration file (typically /etc/dhcp/dhcpd.conf). Without a subnet declaration for 192.168.1.0/24, dhcpd ignores all DHCP traffic on eth0, even though the service is running and listening on UDP port 67. The absence of DHCPOFFER packets despite seeing DHCPDISCOVERs confirms that the server is not processing the requests for that subnet.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.