An instance's system status check fails due to a hardware problem on its underlying host, and automatic instance recovery successfully migrates it to a new host. Compared with an engineer manually stopping and starting the same instance, which detail is different about automatic recovery's outcome?
- Automatic recovery preserves the instance's existing public IPv4 address, while a manual stop and start assigns a new public IPv4 address unless an Elastic IP is attached
- Automatic recovery always loses instance store data, while a manual stop and start always preserves it
- Automatic recovery changes the instance's private IP address, while a manual stop and start keeps it the same
- Automatic recovery moves the instance to a different Availability Zone, while a manual stop and start keeps it in the same one
Why A? And why not the others?
Correct answer: A. Automatic recovery preserves the instance's existing public IPv4 address, while a manual stop and start assigns a new public IPv4 address unless an Elastic IP is attached
Automatic instance recovery is specifically designed so the recovered instance keeps its instance ID, private IP address, public IPv4 address, and any Elastic IP, along with its instance metadata, placement group, and attached EBS volumes — the only things lost are the contents of volatile memory and, for CloudWatch action-based recovery, instance store data. A manual stop and start does not offer the same guarantee for the public IPv4 address: because a standard public IPv4 address isn't static, starting a stopped instance normally assigns it a new one unless an Elastic IP is explicitly associated first, which is the key practical difference between the two approaches. Instance store data is lost in both a manual stop and, for CloudWatch action-based recovery, automatic recovery — it is not preserved by a manual stop as the second option claims. Neither approach changes the instance's private IP address, and automatic recovery specifically keeps the instance within its original Availability Zone rather than moving it elsewhere.
Source: AWS EC2 documentation: Automatic instance recovery — characteristics of recovered instances