PCNE Configuring Network Services Practice Question
A company uses an internal TCP/UDP load balancer to distribute traffic to a backend service. The backend instances are in an unmanaged instance group. Some instances fail health checks and are removed. What happens to existing connections to failed instances?
⚠ Common exam trap
Many exam-takers assume connection draining is always available for load balancers, but Google Cloud tests the distinction between managed and unmanaged instance groups, where unmanaged groups lack graceful connection termination features.
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
✓
Existing connections are terminated immediately.
When an instance in an unmanaged instance group fails a health check, the internal TCP/UDP load balancer immediately terminates all existing connections to that instance. This is because the load balancer does not support connection draining for unmanaged instance groups; it simply stops forwarding new traffic and drops existing flows to the failed instance. The abrupt termination occurs because the load balancer operates at Layer 4 and has no mechanism to gracefully close TCP connections or wait for application-level cleanup.
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 load balancer drains existing connections before removing the instance.
Why it's wrong here
Internal TCP/UDP load balancers do not support connection draining.
- ✗
Existing connections are seamlessly redirected to healthy instances.
Why it's wrong here
The load balancer does not maintain session state for existing connections after instance removal.
- ✓
Existing connections are terminated immediately.
Why this is correct
Internal TCP/UDP load balancers do not provide connection draining; connections are dropped.
- ✗
The load balancer waits for all existing connections to close before removing the instance.
Why it's wrong here
The load balancer removes the instance immediately without waiting.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNE practice question is part of Courseiva's free Google Cloud 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 PCNE exam.