Solved What DHCP Option Tells the DHCP Server the Client's Host name?

Martin McCormick martin at
Tue Jan 22 05:42:46 UTC 2008

Glenn Satchell writes:
> The value you want to read is 'option hostname'.

	I just could not figure out for the life of me why it
wouldn't work. As with those 100-lamp Christmas light strings
wired in series, there wasn't one but two burned-out bulbs to
use the metafore.

	There are two ways to send your host name to DHCP and
they produce identical final results.

	One is via option 12 or host-name. That is what the
Windows clients all seem to do by the thousands. The other is
via an option one can send in dhclient called fqdn.fqdn. If you
really do put a FQDN in there, it botches the name since it
takes the whole string and appends the default-domain-name to it
so you get something like bob.admin.netops.domain instead of
bob.netops.domain or similar.

	You also don't see it in host-name because it isn't

	If you explicitly send the host-name option from
dhclient.conf, the UNIX box is now using the same mechanism to
register its name that all the Win boxes are using.

	I had also failed to set up a variable as Glenn and
others suggested so  both issues combined in series to make it
not work.

	As soon as I set the variable name and also had the test
platform using the correct option, it all worked as expected.

	If you put a FQDN in option 12, it also makes the same
appended mess unless you were looking for that name and set a
class to handle it.

	Also, as soon as I began sending option 12, the name did
began appearing in the system log just like the Win systems.

	Thanks for everybody's help and patience.

Martin McCormick

More information about the dhcp-users mailing list