Configuration Parameters Delivery

The DHCP server is designed to supply DHCP clients with the configuration parameters defined in the Host Requirements RFCs (1122 and 1123). Most of those parameters are related to the TCP/IP protocol stack but DHCP allows the configuration of non-related parameters too.

The server provides a permanent storage of network parameters for network clients. The DHCP storage model is a set of key-value pairs for each client, where the key is some unique identifier and the value contains the configuration parameters for the client. In other words, the storage model is a per-host list of entries of the form:

The client addresses the server with a request message to retrieve its configuration parameters. The server answer with a response message carrying the configuration parameters in the (later discussed) options field.

Not all clients require initialization of all possible parameters. Two techniques are used to reduce the number of parameters delivered from the server to the client:

1. Most of the parameters have defaults defined in the Host Requirements RFCs (1122 and 1123). If the client receives no parameters from the server that override the defaults, a client uses those default values.
2. A client and server may negotiate for the delivery of only those parameters required by the client. In a case like that the client includes the parameter request list option in the requested message and fills it with the list of parameters it needs.

Quiz

1. Configuration parameters are:
   • Stored on a permanent storage device, requested by server.
   • Stored in a 'parameter request list', requested by client.
   • Stored on server, requested by client.

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