A network system automatically distributes management information to allow immediate monitoring. In the network system, the DHCP server of a network-information management server assigns information to a network-information management table when receiving an assignment request of IP information and network management information from a client. The DHCP client of the client obtains the IP information and the network management information from the DHCP server. The SNMP agent of the client reports to a monitoring server that the network management information has been set. The SNMP manager of the monitoring server determines that the network management information has been set, the monitoring control section of the monitoring server records information of the client in a monitoring control table, and starts monitoring the client.