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 system administrator needs to configure bonding in active-backup mode. Which line in /etc/sysconfig/network-scripts/ifcfg-bond0 defines the bonding mode and primary interface?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
BONDING_OPTS="mode=1 primary=eth0 miimon=100"
Option A is correct because it uses the BONDING_OPTS directive with mode=1 (which corresponds to active-backup mode in Linux bonding) and explicitly specifies the primary interface as eth0. The miimon=100 parameter is also included to enable link monitoring via MII (Media Independent Interface) polling every 100 milliseconds, which is essential for failover detection in active-backup mode.
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.
✓
BONDING_OPTS="mode=1 primary=eth0 miimon=100"
Why this is correct
This correctly defines mode=1 (active-backup) with primary eth0 and miimon.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
This is also valid but uses text mode; the question expects numeric mode.
✗
BONDING_OPTS="mode=0 primary=eth0"
Why it's wrong here
Mode=0 is round-robin, not active-backup.
✗
BONDING_OPTS="mode=active-backup miimon=100"
Why it's wrong here
Missing primary interface specification.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the numeric mode values (e.g., mode=1 for active-backup) with the descriptive keywords (e.g., mode=active-backup), or they forget that the primary interface must be explicitly defined in the BONDING_OPTS line to meet the requirement of specifying both the bonding mode and the primary interface.
Detailed technical explanation
How to think about this question
In Linux bonding, mode=1 (active-backup) ensures that only one slave interface is active at a time; the primary parameter designates the preferred interface that becomes active when it is available, and miimon=100 triggers MII link state polling every 100ms to detect failures. Under the hood, the bonding driver uses the MII status register to monitor link state, and when a failure is detected, it automatically fails over to the next available slave. In a real-world scenario, this configuration is critical for high-availability network setups, such as connecting a server to two switches for redundancy, where the primary interface is connected to the primary switch and failover must be seamless.
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: BONDING_OPTS="mode=1 primary=eth0 miimon=100" — Option A is correct because it uses the BONDING_OPTS directive with mode=1 (which corresponds to active-backup mode in Linux bonding) and explicitly specifies the primary interface as eth0. The miimon=100 parameter is also included to enable link monitoring via MII (Media Independent Interface) polling every 100 milliseconds, which is essential for failover detection in active-backup mode.
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: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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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