DHCP received an unknown option 028 of length 004.

[Michael Gederberg]

Hello all... My PDC and BDC's system event log is filling up with the error
mentioned in the suject... Seems I get the error for each node connected to our
network... A Linux server is handling DHCP services though so both NT boxes have
DHCP services disabled... What could be causing this error and how can I fix it?

[Amiri Jones]

"Michael Gederberg" <mich...@spacelab.net> wrote in message
news:aa1201c0817d$cd5a0da0$33862ecf@cpmsftngxa04...

======================================================

Option 28 is the Broadcast Address Option, used to specify the broadcast
address for the client's subnet. This error message is saying that this
machine received a DHCP packet with this option in it, and it doesn't know
what it means. What you need to do is check your DHCP server configuration;
remove option 28 unless there are other computers on the network that need
it.

[Vincent Fatica]

You can also (sort of) tell NT about option 28. It won't actually use it
but it will stop complaining about its being unknown. Below is an excerpt
from an article I wrote on this a couple of years ago, which I found
recently at:

http://x66.deja.com/=dnc/getdoc.xp?AN=517466762&CONTEXT=980208691.1494155431&hitnum=1

Excerpt:

Under:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DHCP\Parameters\Options

I created a key (named for my unknown option) called:

28

Mimicking other "Options" subkeys (have a look at them), I created values
and data in this new key as follows:

(DWORD)
"KeyType" = 7

(STRING)
"RegLocation" =
System\CurrentControlSet\Services\?\Parameters\Tcpip\Unknown28

Note: the "?" belongs there.

I disconnected from the network and stopped/started the DHCP Client service
... (rebooting works too). When restarting, the DHCP Client service created
the "Unknown28" value under the appropriate network adapter registry key and
gave it the data (hex) 3F3F (which is, possibly appropriately, "??"). I have
experienced no problems so far ... and no unwanted event log entries.

(end of excerpt)

- Vince

Vincent Fatica
vefa...@syr.edu
Syracuse University Mathematics
http://barnyard.syr.edu/~vefatica/