F5CAB4 Control Plane Administration Practice Question
Exhibit
tmsh show sys cluster ---------------------------------------------------- Sys::Cluster: default ---------------------------------------------------- State Enabled Status Offline Reason Cluster member is missing heartbeat. [admin@bigip1:Offline] config #
Refer to the exhibit. The cluster status is 'Offline'. What is the most likely reason for this state?
⚠ Common exam trap
Candidates often attribute the 'Offline' state to a configuration sync error, not realizing that heartbeats are a separate, lower-level mechanism required for cluster node communication.
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
✓
Network connectivity for heartbeats is down.
A missing heartbeat is the primary cause of a cluster becoming offline. Heartbeats are the mechanism through which peer devices verify each other's operational status. If the network path for heartbeats is interrupted, the devices cannot verify the health of the peer, leading to an offline state to prevent conflicting traffic processing configurations from being active simultaneously in the network.
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 license is invalid.
Why it's wrong here
An invalid license typically prevents the system from booting or causes modules to stop functioning, but it does not specifically trigger a 'missing heartbeat' error in the cluster status. Heartbeat failures are strictly network-related communication issues between cluster members, not indicators of licensing status or software entitlement problems.
- ✓
Network connectivity for heartbeats is down.
Why this is correct
The error message 'Cluster member is missing heartbeat' directly points to a network communication failure between cluster members. The heartbeat process requires constant reachability over the failover network. If this path is blocked or the peer is down, the system transitions to an Offline state to ensure service safety.
- ✗
The configuration sync has timed out.
Why it's wrong here
While sync issues can be related to network problems, the specific error 'missing heartbeat' is distinct from a 'sync timeout.' Sync timeouts occur when configuration files fail to transfer, whereas heartbeat failures indicate that the cluster members have stopped communicating, which is a more critical, higher-level HA failure.
- ✗
The management plane is overloaded.
Why it's wrong here
An overloaded management plane might slow down response times, but it rarely results in a complete heartbeat failure unless the system is unresponsive. The error clearly indicates a lack of signal between peers, which is typically a connectivity issue at the network level rather than a performance issue.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official F5 exam blueprint
This F5CAB4 practice question is part of Courseiva's free F5 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 F5CAB4 exam.