The DHCP Packet Format And Additional Options

My Top 3

Similar to BOOTP, DHCP uses a request/reply mechanism, and the packet format is almost the same for both to provide for backward compatibility. The layout of the packet used by DHCP looks very much like the layout of the BOOTP packet, with a few exceptions. The first 11 fields are the same. However, the last field, which is called the Vendor Extensions area in the BOOTP packet, is called the Options field in the DHCP packet. The format of the options is the same as it was for BOOTP. However, some of the options that are defined in RFC 2132 are specific only to DHCP. The options available for use with BOOTP clients are a subset of those available for use with DHCP clients. Although this field was limited to 64 bytes in the BOOTP packet, it now is a variable-length field that has a minimum of 312 bytes for DHCP options.