Network configuration servers are the machines that supply the TCP/IP configuration information to hosts configured in network client mode. These servers support three booting protocols:
RARP - Reverse Address Resolution Protocol (RARP) maps known Ethernet addresses (48 bits) to IP addresses (32 bits), the reverse of ARP. When you run RARP on a network configuration server, this enables hosts running in network client mode to obtain their IP addresses and TCP/IP configuration files from the server. The in.rarpd daemon enables RARP services. Refer to the in.rarpd(1M) man page for complete details.
TFTP - Trivial File Transfer Protocol (TFTP) is an application that transfers files between remote machines. The in.tftpd daemon carries out TFTP services, enabling file transfer between network configuration servers and their network clients.
bootparams - The bootparams protocol supplies parameters for booting that are required by diskless clients. The rpc.bootparamd daemon carries out these services.
Network configuration servers can also can function as NFS file servers.
If you are going to configure any hosts as network clients, then you must also configure at least one machine on your network as a network configuration server. If your network is subnetted, then you must have at least one network configuration server for each subnet with network clients.