VPC Managed Prefix Lists

Question

Regarding new feature announced here - https://aws.amazon.com/about-aws/whats-new/2020/06/amazon-virtual-private-cloud-customers-use-prefix-lists-simplify-configuration-security-groups-route-tables/

A customer wishes to know how this affects service limits for Security Groups.
Question: When a rule is created which includes a Prefix List (e.g. as a Source), is this counted as 1 rule or as multiple rules (depending on how many CIDR blocks are declared in the prefix list)?

Accepted Answer

The [documentation][1] indicates this:

When you reference a prefix list in a resource, the maximum number of entries for the prefix lists counts as the same number of rules or entries for the resource. For example, if you create a prefix list with a maximum of 20 entries and you reference that prefix list in a security group rule, this counts as 20 rules for the security group.

[1]: https://docs.aws.amazon.com/vpc/latest/userguide/managed-prefix-lists.html

VPC Managed Prefix Lists

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