The Options

Message Type Offer

A DHCP option marks this toy reply as an offer.

highlighted = computed this step

Options refine the fixed fields

After the magic cookie, option bytes say what kind of DHCP-shaped message this is.

cookie=0x63825363\text{cookie}=0x63825363
Message type optionThe DHCP option bytes are decoded from the pinned toy offer.Message type option160 bits / 20 bytes0x638253633501023604c0a80101330400000e10ffbyte 0byte 1byte 2byte 301100011100000100101001101100011byte 4byte 5byte 6byte 700110101000000010000001000110110byte 8byte 9byte 10byte 1100000100110000001010100000000001byte 12byte 13byte 14byte 1500000001001100110000010000000000byte 16byte 17byte 18byte 1900000000000011100001000011111111magic-cookie0x63825363msg-type-code53msg-type-len1msg-type2server-id-code54server-id-len4server-id192.168.1.1(cont.)lease-code51lease-len4(cont.)lease-time3600end255

Option code names message type

Option 53 is the message-type option. Its length is 1 byte here.

53,153,1
Message type optionThe DHCP option bytes are decoded from the pinned toy offer.Message type option160 bits / 20 bytes0x638253633501023604c0a80101330400000e10ffbyte 0byte 1byte 2byte 301100011100000100101001101100011byte 4byte 5byte 6byte 700110101000000010000001000110110byte 8byte 9byte 10byte 1100000100110000001010100000000001byte 12byte 13byte 14byte 1500000001001100110000010000000000byte 16byte 17byte 18byte 1900000000000011100001000011111111magic-cookie0x63825363msg-type-code53msg-type-len1msg-type2server-id-code54server-id-len4server-id192.168.1.1(cont.)lease-code51lease-len4(cont.)lease-time3600end255

Value two means offer

The message-type value is 2, which marks this toy message as an OFFER-like reply.

message type=2\text{message type}=2
Message type optionThe DHCP option bytes are decoded from the pinned toy offer.Message type option160 bits / 20 bytes0x638253633501023604c0a80101330400000e10ffbyte 0byte 1byte 2byte 301100011100000100101001101100011byte 4byte 5byte 6byte 700110101000000010000001000110110byte 8byte 9byte 10byte 1100000100110000001010100000000001byte 12byte 13byte 14byte 1500000001001100110000010000000000byte 16byte 17byte 18byte 1900000000000011100001000011111111magic-cookie0x63825363msg-type-code53msg-type-len1msg-type2server-id-code54server-id-len4server-id192.168.1.1(cont.)lease-code51lease-len4(cont.)lease-time3600end255

Summary

The fixed field carries reply shape; the option byte says OFFER-like message.

OFFER value=2\text{OFFER value}=2
Message type optionThe DHCP option bytes are decoded from the pinned toy offer.Message type option160 bits / 20 bytes0x638253633501023604c0a80101330400000e10ffbyte 0byte 1byte 2byte 301100011100000100101001101100011byte 4byte 5byte 6byte 700110101000000010000001000110110byte 8byte 9byte 10byte 1100000100110000001010100000000001byte 12byte 13byte 14byte 1500000001001100110000010000000000byte 16byte 17byte 18byte 1900000000000011100001000011111111magic-cookie0x63825363msg-type-code53msg-type-len1msg-type2server-id-code54server-id-len4server-id192.168.1.1(cont.)lease-code51lease-len4(cont.)lease-time3600end255