| Field | Size octets |
Description |
| op | 1 |
op-code 1=request 2=reply |
| htype | 1 |
hardware type e.g 1=10mb ethernet |
| hlen | 1 |
hardware @ length e.g 6=10 Mb ethernet |
| hops | 1 |
counts time request has crossed sub-nets. Use optional. |
| xid | 4 |
transaction id. random - used to recognize reply for this client |
| secs | 2 |
time elapsed since client started to boot |
| flags | 2 |
not currently used(?) |
| ciaddr | 4 |
(client) 0.0.0.0 or client's last remembered IP |
| yiaddr | 4 |
(your IP) IP bootp server is issuing |
| siaddr | 4 |
Server's IP - used for other requests |
| giaddr | 4 |
(gateway) set to 0.0.0.0 by client, used by relay to move request
between sub-nets. |
| chaddr | 16 |
client's hardware (MAC) @ |
| sname | 64 |
Server's DNS name (optional) |
| file | 128 |
boot file name - used for systems that network booted. |
| vend | 64 |
optional vendor provided information |