ANS-C01 Network Management and Operations Practice Question
Network Topology
Refer to the exhibit. A network engineer created a NAT gateway in a public subnet, but its state shows 'failed'. What is the most likely cause?
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
✓
The Elastic IP is already associated with another instance
A NAT gateway requires an Elastic IP that is not associated with any other resource. If the Elastic IP is already associated with another instance or NAT gateway, the NAT gateway creation fails. Option A is incorrect because the subnet must have a route to an internet gateway to be public, but that is not the cause of the failure. Option B is incorrect because the NAT gateway is explicitly placed in a public subnet. Option C is incorrect because the state 'failed' indicates the creation did not succeed, not that it is still pending.
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 subnet does not have a route to an internet gateway
Why it's wrong here
The presence of a public IP suggests the subnet is public and has a route to IGW.
- ✗
The subnet is private
Why it's wrong here
The subnet is public (has public IP allocated).
- ✗
The NAT gateway is still being created
Why it's wrong here
State is 'failed', not 'pending'.
- ✓
The Elastic IP is already associated with another instance
Why this is correct
A NAT gateway requires an unassociated Elastic IP.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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