A scan client in a subnet of an intranet may be designated as a root agent to provide subnet information to a scan server in the intranet. The subnet information may include addresses of computers belonging to the subnet. The scan server may use subnet information collected from various root agents to build a map of the intranet. The intranet map may be forwarded from the scan server to the root agents, which in turn provide the intranet map to scan clients in their respective subnets. The root agents may also receive antivirus modules from the scan server for distribution to scan clients. A scan client may look for computers indicated in the intranet map to determine whether or not it is connected to the intranet.