3.2.5.3 Receiving a DHCPINFORM Message
The DHCPINFORM message SHOULD<7> be processed as specified in section 3.2.5.2.4; when a DHCP server that is NAP-enabled (determined per section 1.4 points 1 and 2) receives a DHCPINFORM message, it extracts the NAP-SoH (section 2.2.1.1) and NAP-CoID (section 2.2.1.3) options from the message packet by calling DhcpExtractVendorSpecificOption ([MS-DHCPE] section 3.2.7.3).
It SHOULD respond back to a DHCPINFORM message from the client containing the SoH token in the NAP-SoH option with a DHCPACK message containing a NAP-SoH option containing the non-null-terminated string "NAP" of length 3 in network byte order and the NAP-CoID (section 2.2.1.3) option as it is in the DHCPINFORM message packet. The NAP-SoH (section 2.2.1.1) is appended to the DHCPACK message packet by calling DhcpAppendVendorSpecificOption ([MS-DHCPE] section 3.2.7.1).