The Offer

XID and Client MAC

The offer-shaped reply keeps the transaction id and client hardware address visible.

highlighted = computed this step

The reply carries the same transaction

This toy OFFER-like reply carries transaction id 0x12345678 so the requester can match the reply to its question.

xid=0x12345678\text{xid}=0x12345678
Transaction and clientThe toy DHCP OFFER-like fixed fields are decoded from exact bytes.Transaction and client144 bits / 18 bytes0x0201060012345678c0a80132001122334455byte 0byte 1byte 2byte 300000010000000010000011000000000byte 4byte 5byte 6byte 700010010001101000101011001111000byte 8byte 9byte 10byte 1111000000101010000000000100110010byte 12byte 13byte 14byte 1500000000000100010010001000110011byte 16byte 170100010001010101op2htype1hlen6hops0xid0x12345678yiaddr192.168.1.50chaddr0x001122334455(cont.)

Operation says reply

The op field is 2, so this byte string is a reply-shaped message, not a request-shaped message.

op=2\text{op}=2
Transaction and clientThe toy DHCP OFFER-like fixed fields are decoded from exact bytes.Transaction and client144 bits / 18 bytes0x0201060012345678c0a80132001122334455byte 0byte 1byte 2byte 300000010000000010000011000000000byte 4byte 5byte 6byte 700010010001101000101011001111000byte 8byte 9byte 10byte 1111000000101010000000000100110010byte 12byte 13byte 14byte 1500000000000100010010001000110011byte 16byte 170100010001010101op2htype1hlen6hops0xid0x12345678yiaddr192.168.1.50chaddr0x001122334455(cont.)

Client hardware address is included

The client hardware address is 0x001122334455. The hardware length field says it is 6 bytes.

hlen=6,chaddr=0x001122334455\text{hlen}=6,\quad \text{chaddr}=0x001122334455
Transaction and clientThe toy DHCP OFFER-like fixed fields are decoded from exact bytes.Transaction and client144 bits / 18 bytes0x0201060012345678c0a80132001122334455byte 0byte 1byte 2byte 300000010000000010000011000000000byte 4byte 5byte 6byte 700010010001101000101011001111000byte 8byte 9byte 10byte 1111000000101010000000000100110010byte 12byte 13byte 14byte 1500000000000100010010001000110011byte 16byte 170100010001010101op2htype1hlen6hops0xid0x12345678yiaddr192.168.1.50chaddr0x001122334455(cont.)

Summary

The xid and client MAC tie this offer-shaped message to one requester.

xid=0x12345678\text{xid}=0x12345678
Transaction and clientThe toy DHCP OFFER-like fixed fields are decoded from exact bytes.Transaction and client144 bits / 18 bytes0x0201060012345678c0a80132001122334455byte 0byte 1byte 2byte 300000010000000010000011000000000byte 4byte 5byte 6byte 700010010001101000101011001111000byte 8byte 9byte 10byte 1111000000101010000000000100110010byte 12byte 13byte 14byte 1500000000000100010010001000110011byte 16byte 170100010001010101op2htype1hlen6hops0xid0x12345678yiaddr192.168.1.50chaddr0x001122334455(cont.)