[Dnsmasq-discuss] I want to try and set up a DHCP "server" to handle one subnet

[Simon Kelley]

On 04/01/12 22:06, Matt Ginzton wrote:
>>> How to restrict my server's DHCP offerings to a single subnet.
>>>
>>> How must the Other DHCP server and routers be modified to permit this.
>>> ?? Disable DHCP relay to/from this subnet ??
>>
>> That's it. DHCP won't go outside a "broadcast domain" without a DHCP
>> relay, so if the main DHCP server is on another subnet, then there must
>> be a DHCP relay. Stop that and there will be no DHCP service from the
>> main DHCP server on your subnet.
> 
> Don't you want to distinguish between subnet (layer 3 concept) and segment
> (layer 2 concept) here? 

I maybe should have done, yes.

> There may be people who've set up multiple subnets
> just by IP addressing, on the same L2 ethernet segment, and at this point
> assuming there's no DHCP interference would be dangerous.
> 
> Assuming ethernet, it's the L2 concept (ethernet segment) that will determine
> the broadcast domain.
> 
> Basically, make sure your different subnets are also on different ethernet
> segments, then the broadcast domains will be separate and DHCP will be
> separate as you'd expect.
> 

That's true.

Cheers,

Simon.