We have briefly looked at transport zones in the previous chapters. A transport zone controls the domain of a logical switch among the hosts. In other words, it controls which hosts a logical switch can reach. A transport zone is configured on a per-cluster basis and can span multiple clusters in a vCenter. A universal transport zone can span multiple clusters across multiple vCenters. A transport zone dictates which host and, by extension, which virtual machines are allowed to participate in a particular network. In a typical environment, there can be more than one transport zone that is mapped to a host or to a cluster. However, a logical switch can only belong to one transport zone.

If a virtual machine belongs to a different transport zone, you will not be able to directly communicate with that virtual machine. This means that a vNIC is limited to spanning...