Subnetwork are a term used in reference with which of the following?

What I know about the subnetworking it is term from IT Network 

Subnetwork or subnet is a term usually related to Internet networking, but this term can also be used to refer to Levels of WBS under one main WBS.

allotted Job / Task , Completion with achievement with in or above fixed time frame , must be recorded in achievement

When a reference is invited or required, then sub-network term is used

D. Network templates