AWS Certified SysOps Administrator Practice Exam

In an AWS VPC, what happens if a public IP address of an instance is released?

1. The instance will automatically get a new public IP

2. The instance will not receive a new public IP if multiple interfaces are attached

3. The public IP can always be released and re-associated

4. Instances cannot hold public IPs for more than 30 days

The correct answer is: The instance will not receive a new public IP if multiple interfaces are attached

In an AWS VPC, when a public IP address of an instance is released, the instance will not automatically receive a new public IP if multiple network interfaces are attached. In scenarios where an instance has an Elastic IP address allocated, releasing the public IP does not impact the Elastic IP, as it remains associated with the instance until explicitly disassociated. A key reason why the correct answer emphasizes that an instance will not receive a new public IP if it has multiple interfaces is based on how AWS handles public IP assignments. When an instance is launched, it can be assigned a public IP from the pool of available addresses in the subnet. If that IP is released, and since multiple interfaces do not necessarily mean that each has a public IP associated, the instance won't automatically acquire a new public IP without the appropriate configurations or actions being taken. In contrast, other options do not accurately reflect the mechanics of AWS regarding public IP address assignment. It is important to note that public IPs can expire or be released, but an instance won't necessarily get a brand new one within a multi-interface setup unless specifically configured to obtain one. Understanding this behavior is crucial for managing network configurations in AWS effectively.