3.1.4.2 Creating and Transmitting a DHCPREQUEST Message During Lease Renewal
Whenever a DHCP client sends a DHCPREQUEST message during DHCP lease renewal and its NAP-Capable Server state is set to "Unknown" or "Yes", it MUST include the NAP-SoH (section 2.2.1.1) option of length one octet and data equal to zero in the DHCPREQUEST message. It MUST also include a NAP-CoID (section 2.2.1.3) option in this message.
If instead the NAP-Capable Server state is set to "No", it MUST send the message without any options defined in this document.