Updating DNS after DHCP

[Gilad Rom]

Scott Mitchell wrote:
> On Tue, Jan 13, 2004 at 01:16:23PM +0100, Ruben de Groot wrote:
> 
>>On Mon, Jan 12, 2004 at 11:09:38PM -0600, John typed:
>>
>>>I see that some Microsoft systems send out an update to DNS with
>>>the system name.  I configured my DNS server to accept these updates,
>>>but now that I'm running FreeBSD on a laptop - how do I do that
>>>from FreeBSD? I've looked at the dhclient man pages and the named
>>>man pages and the pages that they refer to and I didn't pick up
>>>any hints there.
>>>
>>>Can anyone give me a clue? (Yeah - I'm clueless...)
>>
>>I believe this is done by the nsupdate(8) program.
> 
> 
> You can also have your DHCP server do the updates - which makes sense, as
> it's the thing handing out the addresses to your client machines.  I have
> this working reasonably well with isc-dhcpd, for Windows and FreeBSD
> clients.
> 
> You want to read the 'DYNAMIC DNS UPDATES' section of the dhcpd.conf(5)
> manpage, and whatever docs your DNS server has on this topic.  There are
> plenty of examples of working configs for isc-dhcpd and bind to be found on
> the web.
> 
> HTH,
> 
> 	Scott
> 

I just set this up today...
There's actually nothing to be done on the client side.
The isc-dhcp server takes care of informing BIND that it has handed
out a new Address.

You have to add the following line to your dhcpd.conf:
ddns-update-style ad-hoc;

and make sure BIND is willing to take it:
(from /etc/named/named.conf:

zone "lan" {
         type master;
         allow-update { 192.168.1.10; }; <<--
         file "s/lan";
};

(192.168.1.10 is my DHCP server, which is actually
the same machine which runs BIND)

after a little while, 'host -l lan' says:
OREN1.lan has address 192.168.1.54
ROIE.lan has address 192.168.1.57
Sun.lan has address 192.168.1.56
zhacy.lan has address 192.168.1.58
....
And so forth...

These are all dynamically-assigned addresses,
I only have ladon/mail/router.lan defined in the
zone file.

Gilad.