To secure security and reduce network manager's labor for network setting in a network management system using a DHCP system and a DNS system.

In the network management system which has a DHCP server and dynamically delivers IP addresses to DHCP clients by DHCP, the DHCP server is provided with a DHCP cooperation server for registering information of DHCP clients to which IP addresses will be delivered, and host names, MAC addresses, and network segments of the clients are set as DHCP setting information. In the DNS system, DNS information is generated in a DNS cooperation server and is allowed to be semi-automatically registered in a DNS server.