# Identifying subnet and Availability Zone requirements
<a name="vpc-out-AZ-subnet-reqs"></a>

Subnets and Availability Zones apply as follows:
+ **Inputs **– Some MediaLive input types are in your VPC, which means that they are in a specific subnet. For example, an RTMP input can be in your VPC. For more information, see [Input types, protocols, and upstream systems](inputs-supported-formats.md).
+ **Endpoints** – The channel endpoints are in a subnet. 
+ **Destinations** –The IP addresses for outputs in the VPC are in a subnet.

You must identify the VPCs and subnets for the MediaLive endpoints and for those of your output destinations that are an address in your VPC. You must consider the following:
+ You must make sure that the setup follows the rules for allocation across subnets and across Availability Zones. See [Use case A – no VPC inputs](vpc-out-caseA.md) and the section that follows it.
+ Each subnet must have a private CIDR block (a range of IP addresses).
+ Each subnet must have at least two unused addresses in that block. 

**Topics**
+ [Use case A – no VPC inputs](vpc-out-caseA.md)
+ [Use case B – channel includes VPC inputs](vpc-out-caseB.md)