[TriLUG] DHCP/DNS

Chris Hedemark chris at yonderway.com
Thu Apr 25 09:11:48 EDT 2002


On Thu, 2002-04-25 at 00:57, Andy Hart wrote:

> I need a little help. I just bought a D-Link router that I'm connecting to a
> Cable Modem. I have it configured to be a DHCP server. On my linux box, I'd
> like to setup DNS, but how, the IP addresses are created dynamically?
> What's the answer?

Q) How can you set the DNS address to point to your own machine if its
own address is dynamic?
A1) If your firewall supports it, try setting up a DHCP reservation for
your DNS server so it will always get the same address.
A2) Use a static IP address for your DNS server outside of the range of
DHCP addresses yet on the same subnet.

The other issue you might run into is that some firewall appliances
won't let you change the DHCP scope options sufficiently to use your own
DNS server (rather, it uses data harvested from its own internal DHCP
client on the external interface and passes the DNS server value from
that).  If this is the case, you may need to hardcode the DNS address on
all of your clients but use DHCP for everything else.

You will get some differing opinions on this last point for certain, but
I have to recommend to you to consider using a low end PC as a firewall
which will give you far more options and IMHO allow you to more easily
update your firewall to adapt to ever changing threats.





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