# Optimal instance type configuration to receive automatic instance family updates
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**Note**  
Starting on 11/01/2025 the behavior of `optimal` is going to be changed to match `default_x86_64`. During the change your instance families could be updated to a newer generation. You do not need to perform any actions for the upgrade to happen.

AWS Batch supported a single option in **instanceTypes** for `optimal` to match the demand of your job queues. We've introduced two new instance type options: `default_x86_64` and `default_arm64`. We will use `default_x86_64` if you make no instance type selection. These new options will automatically select cost-effective instance types across different families and generations based on your job queue requirements, allowing you to get your workloads running quickly.

As sufficient capacity of new instance types become available in an AWS Region, the corresponding default pool will be automatically updated with the new instance type. The existing `optimal` option will continue to be supported and is not being deprecated, as it will be supported by the underlying default pools to provide updated instances going forward. If you are using '`optimal`, no action is needed on your part.

However, please be aware that only `ENABLED` and `VALID` Compute Environments (CEs) will be automatically updated with new instance types. If you have any `DISABLED` or `INVALID` CEs, they will receive updates once they are re-enabled and set to a `VALID` state.