[BBLISA] A question on DHCP "shoulds".

[Dewey Sasser]

John Hanks wrote:
> On Mon, Aug 31, 2009 at 9:15 AM, Edward Ned Harvey<bblisa3 at nedharvey.com> wrote:
>   
>>> I know that I can tell a DHCP server that machine with MAC address
>>> [bla] is to always get IP address [foo] this seems straight forward
>>> but the question is, if machine with MAC address [bla] treats it's IP
>>> address as statically assigned, as in, it's hardwritten into the
>>> configuration/startup scripts, does that "violate" (for lack of a
>>> better term) the rules of DHCP?
>>>       
>> Absolutely no problem.  I do this all the time, and here are the reasons
>> why:
>>     
>
> I'm going to take the opposing viewpoint, if only to make this a more
> lively discussion.
>
> My opinion is that the only machines in an environment that should be
> set statically are the DHCP and DNS servers and, if these are
> virtualized, the hosts which make up the virtualization
> infrastructure. My view of a network infrastructure places DHCP and
> DNS at the foundation. 
I took this approach in the last network I set up from scratch.  I put
static assignments by MAC into my DHCP server.

I found two problems with it:

1) Some system (e.g. some VMWare products, Oracle), really, don't like
being installed with a DHCP address.  I recall on some installations
this was a warning and others absolutely refused to install with a DHCP
interface.  I believe that decision is outside the scope of an installer.

2) At one point I was overly enthusiastic with the copy-and-paste and
ended up with duplicate MAC addresses in my DHCP assignments file.  This
caused a problem, but not until the next DHCP renew cycle.  I since
added a validator to ensure MAC uniqueness.

>> If a linux machine is a dhcp client, then the linux machine will assign
>> itself whatever hostname the dhcp server says. 
I believe this is distro specific.  I'm running many Ubuntu Server
configurations that do not do this.

I don't have anything which requires it's own hostname in /etc/hosts so
I haven't had to deal with this problem.  (Well, I've got a
non-production Oracle in a small cage in a VMWare virtual network, and
it might require this) .

FWIW
--
Dewey