3Com MSR 50 Series Configuration Manual page 2173

command, refer to "DNS Configuration" on page
temporary configuration is to execute the undo ip host command to remove
the temporary configuration.
For the detailed introduction to DHCP, refer to
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Obtaining the configuration files from the TFTP server
The device can obtain the following configuration files from the TFTP server with
the automatic configuration function enabled:
The configuration file specified by the Option 67 or file field in the DHCP
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response
The intermediate file which contains the mapping between the IP address and
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the host name, with the file name as "network.cfg"
The configuration file corresponding with the host name of the device, with its
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file name as "hostname.cfg". For example, if the host name of the device is
aaa, then the configuration file name is "aaa.cfg".
Default configuration file, with the name as "device.cfg"
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The device obtains the configuration files from the TFTP server based on its
resolution of the configuration file name in the DHCP response:
If the DHCP response contains information such as configuration file name, the
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device requests for the specified configuration file to the TFTP server.
If no information such as configuration file name is contained in the DHCP
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response, the device should obtain its host name first and then requests for the
configuration file corresponding with the host name. The device can obtain its
host name in two ways: obtaining the intermediate file from the TFTP server or
searching in the intermediated file for its host name corresponding with the IP
address of the device; if fails, the device obtains the host name from the DNS
server.
If the device fails to obtain the specified configuration file, resolute its host
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name or fails to obtain the configuration file corresponding with the host
name, it requests for the default configuration file to the TFTP server.
Sending mode of the TFTP request
The device selects the sending mode of the TFTP request based on its resolution of
the TFTP server's domain name and IP address in the DHCP response:
If a legitimate TFTP server IP address is contained in the DHCP response, the
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device unicasts a TFTP request to the TFTP server and does not resolve the
domain name of the TFTP server. Otherwise, the device resolves the TFTP
domain name.
If a legitimate TFTP server domain name is contained in the DHCP response, the
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device resolves the IP address of the TFTP server through DNS server. If
succeeds, the device unicasts a TFTP request to the TFTP server; if fails, the
device broadcasts a TFTP request to the TFTP server.
If the IP address and the domain name of the TFTP server are not contained in
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the DHCP response or they are illegitimate, the device broadcasts a TFTP
request to the TFTP server.
Introduction to Automatic Configuration
609) Removal of the
"DHCP Overview" on page
2173
565.