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.
A server with two network interfaces (eth0 and eth1) needs to be configured as a bridge (br0) to allow KVM virtual machines to share the host's physical network. Which steps are correct?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create bridge br0, add eth0 as port, assign IP to br0, remove IP from eth0.
Option A is correct because bridging requires the physical interface (eth0) to be added as a port to the bridge (br0) without an IP address, while the bridge itself gets the IP address to act as the network layer endpoint. This allows KVM virtual machines connected to br0 to communicate through eth0, which operates at layer 2. Removing the IP from eth0 prevents IP conflicts and ensures all traffic is handled by the bridge.
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.
✓
Create bridge br0, add eth0 as port, assign IP to br0, remove IP from eth0.
Why this is correct
This is the standard procedure for configuring a bridge with a physical interface.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create bridge br0, add eth0 as port, assign IP to eth0, do not assign IP to br0.
Why it's wrong here
The IP address must be assigned to the bridge interface, not the physical port.
✗
Create bond0 from eth0 and eth1, then add bond0 to bridge br0.
Why it's wrong here
This combines bonding and bridging, which is not required for a simple bridge setup.
✗
Create bridge br0, add eth0 and eth1 as bridge ports, assign IP to br0, remove IP from eth0 and eth1.
Why it's wrong here
Adding both interfaces is unnecessary; typically only one physical interface is used as a bridge port.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think the physical interface must retain its IP address or that both interfaces must be added to the bridge, confusing bridging with routing or bonding.
Detailed technical explanation
How to think about this question
Under the hood, a Linux bridge operates as a virtual switch at layer 2, using the bridge-utils or iproute2 commands (e.g., `brctl` or `ip link`). When a physical interface like eth0 is added as a bridge port, it becomes a slave to the bridge and loses its own IP configuration; the bridge itself then handles ARP and IP traffic. In KVM, the bridge is typically configured via libvirt or directly with `virsh`, and the host's network connectivity is maintained through the bridge IP, while VMs use the bridge as their virtual switch to access the external network.
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 practitioner preparing for the LFCS 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
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: Create bridge br0, add eth0 as port, assign IP to br0, remove IP from eth0. — Option A is correct because bridging requires the physical interface (eth0) to be added as a port to the bridge (br0) without an IP address, while the bridge itself gets the IP address to act as the network layer endpoint. This allows KVM virtual machines connected to br0 to communicate through eth0, which operates at layer 2. Removing the IP from eth0 prevents IP conflicts and ensures all traffic is handled by the bridge.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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