For improved security, avoid putting the vCenter Server system on any network other than the management network, and ensure that vSphere management traffic is on a restricted network. By limiting network connectivity, you limit certain types of attack.
vCenter Server requires access to the management network only. Avoid putting the vCenter Server system on other networks such as your production network or storage network, or on any network with access to the Internet. vCenter Server does not need access to the network where vMotion operates.
vCenter Server requires network connectivity to the following systems.
All ESXi hosts.
The vCenter Server database.
Other vCenter Server systems (linked mode only)
Systems that are authorized to run management clients. For example, the vSphere Web Client, a Windows system where you use the PowerCLI, or any other SDK-based client.
Systems that run add-on components such as VMware vSphere Update Manager.
Infrastructure services such as DNS, Active Directory, and NTP.
Other systems that run components that are essential to functionality of the vCenter Server system.
Use a local firewall on the Windows system where vCenter Server system is running or use a network firewall. Include IP-based access restrictions so that only necessary components can communicate with the vCenter Server system.