I think you can configure your
dhclient via the `/etc/dhclient.conf file telling it which options you want it to formally request values for from your DHCP server.
request subnet-mask, broadcast-address, routers, domain-name,
You can find out more about this via the
dhclient.conf man page.
There is a variety of data contained in offers that DHCP servers send to
DHCP clients. The data that can be specifically requested is what are
called DHCP Options. DHCP Options are defined in dhcp-options(5).
The request statement
[ also ] request [ [ option-space . ] option ] [, ... ];
The request statement causes the client to request that any server
responding to the client send the client its values for the
specified options. Only the option names should be specified in the
request statement - not option parameters. By default, the DHCPv4 client
requests the subnet-mask, broadcast-address, time-offset, routers,
domain-search, domain-name, domain-name-servers, host-name, nis-domain,
nis-servers, ntp-servers and interface-mtu options while the DHCPv6 client
requests the dhcp6 name-servers and domain-search options. Note that if you
enter a ´request´ statement, you over-ride these defaults and these options
will not be requested.
In some cases, it may be desirable to send no parameter request list at all.
To do this, simply write the request statement but specify no
In most cases, it is desirable to simply add one option to the request list
which is of interest to the client in question. In this case, it is best to
´also request´ the additional options:
also request domain-search, dhcp6.sip-servers-addresses;
Disabling via /dhclient-exit-hooks.d?
Poking around a 12.10 install of Ubuntu I noticed this directory,
/etc/dhcp/dhclient-exit-hooks.d with this file inside it,
ntpdate. Looking at this file it contains a shell script that will perform the update on a system when a lease is acquired or released via DHCP. You could disable the updating of your NTP server through this script, by simply commenting out this file:
case $reason in