AWS Network Firewall - Recommended Subnet Size?

Question

Hi all,
I'm in the process of implementing AWS Network Firewall in my test environment and, while I understand that the Network Firewall must be launched into its own subnet, there's nothing saying how big or small this subnet should be. Does it matter? Is there a reason to size the subnet in any particular manner? 
Thanks!

Yaniv Rozenboim · Accepted Answer

Since the Network Firewall endpoint will be the only resource within that subnet, the smallest subnet possible in a VPC would be enough - **/28**.

Also, have a look at the [Inspection Deployment Models with AWS Network Firewall reference architecture
](https://d1.awsstatic.com/architecture-diagrams/ArchitectureDiagrams/inspection-deployment-models-with-AWS-network-firewall-ra.pdf).
You can see all examples there have /28 subnet for the firewall subnet.

AWS Network Firewall - Recommended Subnet Size?

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