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82Switched Rack PDU User Guide
DHCP response options
Each valid DHCP response contains options that provide the TCP/IP settings that the Rack PDU needs to
operate on a network, and other information that affects the operation of the Rack PDU.
Vendor Specific Information (option 43). The Rack PDU uses this option in a DHCP response to
determine whether the DHCP response is valid. This option contains an APC-specific options in a TAG/
LEN/DATA format, called the APC Cookie. This is disabled by default.
• APC Cookie. Tag 1, Len 4, Data “1APC”
Option 43 communicates to the Rack PDU that a DHCP server is configured to service
devices.
Following, in hexadecimal format, is an example of a Vendor Specific Information option that
contains the APC cookie:
Option 43 = 0x01 0x04 0x31 0x41 0x50 0x43
TCP/IP options. The Rack PDU uses the following options within a valid DHCP response to define its
TCP/IP settings. All of these options except the first are described in RFC2132.
• IP Address (from the yiaddr field of the DHCP response, described in RFC2131): The IP
address that the DHCP server is leasing to the Rack PDU.
• Subnet Mask (option 1): The Subnet Mask value that the Rack PDU needs to operate on the
network.
• Router, i.e., Default Gateway (option 3): The default gateway address that the Rack PDU needs to
operate on the network.
• IP Address Lease Time (option 51): The time duration for the lease of the IP Address to the Rack
PDU.
• Renewal Time, T1 (option 58): The time that the Rack PDU must wait after an IP address lease is
assigned before it can request a renewal of that lease.
• Rebinding Time, T2 (option 59): The time that the Rack PDU must wait after an IP address lease
is assigned before it can seek to rebind that lease.
Other options. The Rack PDU also uses these options within a valid DHCP response. All of these
options except the last are described in RFC2132.
• Network Time Protocol Servers (option 42): Up to two NTP servers (primary and secondary)
that the Rack PDU can use.
• Time Offset (option 2): The offset of the Rack PDU's subnet, in seconds, from Coordinated
Universal Time (UTC).
• Domain Name Server (option 6): Up to two Domain Name System (DNS) servers (primary and
secondary) that the Rack PDU can use.
• Host Name (option 12): The host name that the Rack PDU will use (32-character maximum
length).
• Domain Name (option 15): The domain name that the Rack PDU will use (64-character
maximum length).
• Boot File Name (from the file field of the DHCP response, described in RFC2131): The fully
qualified directory-path to a user configuration file (.ini file) to download. The siaddr field of the
DHCP response specifies the IP address of the server from which the Rack PDU will download
the .ini file. After the download, the .ini file is used as a boot file to reconfigure the settings.