3Com 4210G Series Configuration Manual page 1130

The configuration file name is saved in the Option 67 or file field of the DHCP response. The
device first resolves the Option 67 field; if this field contains the configuration file name, the device
does not resolve the file field; otherwise, it resolves the file field.
Temporary configuration contains two parts: the configuration on the interface where automatic
configuration is performed when the device starts up with default configuration; and the executed
ip host command when the device is resolving the network intermediate file (For the detailed
description of the ip host command, refer to Domain Name Resolution Commands in the IP
Services Volume.). Removal of the temporary configuration is to execute the undo commands.
For the detailed introduction to DHCP, refer to DHCP Configuration in the IP Services Volume.
Principles for selecting an address pool on the DHCP server
The DHCP server selects IP addresses and other network configuration parameters from an address
pool when assigning an IP address to a client. DHCP supports two mechanisms for IP address
allocation.
Dynamic address allocation: The DHCP server assigns an IP address and other configuration
parameters in an address pool to a client.
Manual address allocation: The DHCP server will select an address pool where an IP address is
statically bound to the MAC address or ID of the client and assign the statically bound IP address
and other configuration parameters to the client.
You can configure an address allocation mode as needed:
Different devices with the same configuration file: You can configure dynamic address allocation
on the DHCP server to assign IP addresses and the same configuration parameters (for example,
configuration file name) to the devices. If this address allocation mode is adopted, the
configuration file can only contain common configurations of the devices, and the specific
configurations of each device need to be performed in other ways. For example, you need to
specify to enable Telnet on a device through the configuration file obtained in automatic
configuration and create a local user to facilitate the administrator to Telnet to each device to
perform specific configurations (for example, configure the IP address of each interface).
Different devices with different configuration files: You need to configure an address pool where
an IP address is statically bound to the MAC address or ID of the client, to ensure that a specific
client can be assigned with a fixed IP address and other configuration parameters. Through this
address allocation mode, you can specify different configuration commands for each device,
without the need to configure the device through other modes.
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