Stateful and stateless environment:
1. Keep your ISO in https location and setup the Scripted environment to boot all the host from the same ESXi ISO. All host boot with the same Build. VMware KB: Deploying ESXi 5.x using the Scripted Install feature
2. If you want the stateless environment then setup the auto deploy server in vCenter Server and Boot all host with the same auto deploy server keeping the same ISO. VMware KB: Understanding vSphere Auto Deploy Stateless Caching and Stateful Installs