- A
BONDING_OPTS="mode=1 primary=eth0 miimon=100"
Correct. This line uses the numeric mode value '1' for active-backup, which is a standard format. It explicitly defines the primary interface (eth0) and includes the miimon parameter.
- B
BONDING_OPTS="miimon=100 mode=active-backup primary=eth0"
Correct. This line uses the textual mode name 'active-backup', which is also a recognized value in bonding configuration. It sets the primary interface and miimon, meeting the requirement.
- C
BONDING_OPTS="mode=0 primary=eth0"
Why wrong: Incorrect. Mode 0 corresponds to round-robin (balance-rr), not active-backup. Additionally, it lacks the miimon parameter.
- D
BONDING_OPTS="mode=active-backup miimon=100"
Why wrong: Incorrect. Although it sets mode=active-backup and miimon, it does not specify a primary interface, which is required to define the primary interface.
LFCS Networking Practice Question
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 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
BONDING_OPTS="mode=1 primary=eth0 miimon=100"
Options A and B are both correct. Both lines use BONDING_OPTS to set the bonding mode and primary interface. Option A uses the numeric mode value 'mode=1', which is the standard numeric representation for active-backup. Option B uses the textual value 'mode=active-backup', which is also valid in many Linux distributions (e.g., RHEL/CentOS). Both include the primary interface (eth0) and the miimon parameter. Options C and D are incorrect because option C uses mode=0 (round-robin) and lacks miimon, and option D omits the primary interface specification.
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
Correct. This line uses the numeric mode value '1' for active-backup, which is a standard format. It explicitly defines the primary interface (eth0) and includes the miimon parameter.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
BONDING_OPTS="miimon=100 mode=active-backup primary=eth0"
Why this is correct
Correct. This line uses the textual mode name 'active-backup', which is also a recognized value in bonding configuration. It sets the primary interface and miimon, meeting the requirement.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
BONDING_OPTS="mode=0 primary=eth0"
Why it's wrong here
Incorrect. Mode 0 corresponds to round-robin (balance-rr), not active-backup. Additionally, it lacks the miimon parameter.
- ✗
BONDING_OPTS="mode=active-backup miimon=100"
Why it's wrong here
Incorrect. Although it sets mode=active-backup and miimon, it does not specify a primary interface, which is required to define the primary interface.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap is that candidates may assume only numeric mode values are correct, but many Linux distributions accept both numeric (mode=1) and textual (mode=active-backup) representations. Both are valid for active-backup bonding mode.
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.
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FAQ
Questions learners often ask
What does this LFCS question test?
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" — Options A and B are both correct. Both lines use BONDING_OPTS to set the bonding mode and primary interface. Option A uses the numeric mode value 'mode=1', which is the standard numeric representation for active-backup. Option B uses the textual value 'mode=active-backup', which is also valid in many Linux distributions (e.g., RHEL/CentOS). Both include the primary interface (eth0) and the miimon parameter. Options C and D are incorrect because option C uses mode=0 (round-robin) and lacks miimon, and option D omits the primary interface specification.
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.
About these practice questions
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Last reviewed: Jun 25, 2026
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