This LFCS practice question tests your understanding of networking. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Which bonding mode provides high availability without requiring switch configuration?
mode 1 (active-backup)
Active-backup uses only one NIC at a time; no switch configuration needed.
mode 4 (802.3ad)
Why wrong: 802.3ad requires LACP support on the switch.
mode 6 (balance-alb)
Why wrong: Balance-alb is outbound load balancing without switch support but does not provide high availability per se.
mode 0 (balance-rr)
Why wrong: Balance-rr requires switch to support link aggregation or may cause issues.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
mode 1 (active-backup)
Mode 1 (active-backup) provides high availability by designating one NIC as active and the others as standby, with automatic failover if the active link fails. It requires no special switch configuration because it does not use any link aggregation protocol or load-balancing algorithm that depends on switch-side settings.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
mode 1 (active-backup)
Why this is correct
Active-backup uses only one NIC at a time; no switch configuration needed.
Related concept
Read the scenario before looking for a memorised answer.
mode 4 (802.3ad)
Why it's wrong here
802.3ad requires LACP support on the switch.
mode 6 (balance-alb)
Why it's wrong here
Balance-alb is outbound load balancing without switch support but does not provide high availability per se.
mode 0 (balance-rr)
Why it's wrong here
Balance-rr requires switch to support link aggregation or may cause issues.
Common exam traps
The trap here is that candidates often confuse 'high availability' with 'load balancing' and choose mode 0 or mode 4, not realizing that those modes require switch configuration or do not inherently provide failover without additional setup.
Detailed technical explanation
Under the hood, active-backup bonding uses a single MAC address for all slaves, so the switch sees only one MAC per port, avoiding any need for switch-side LACP or static aggregation. Failover is handled entirely by the bonding driver, which monitors link status via MII (Media Independent Interface) monitoring and can also use ARP monitoring to detect upstream failures. In a real-world scenario, this mode is ideal for connecting to unmanaged switches or switches where you cannot modify port-channel settings.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Networking — This question tests Networking — Read the scenario before looking for a memorised answer..
The correct answer is: mode 1 (active-backup) — Mode 1 (active-backup) provides high availability by designating one NIC as active and the others as standby, with automatic failover if the active link fails. It requires no special switch configuration because it does not use any link aggregation protocol or load-balancing algorithm that depends on switch-side settings.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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.
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