dhcp client and dns bind question

[Mike Klein]

feenberg at gmail.com wrote:
> ChangShen wrote:
>> Hi all,
>> I have a naive question.
> 
> Somehow computer documentaion often omits the basics.
> 
>> How a dhcp client's information get into dns
>> or bind server?
> 
> The DNS server (named) is normally controlled by a static file
> /etc/named.conf
> and the zone files in /var/named however there is a procedure called
> "dynamic DNS" for clients to update their DNS information on the fly.
> 
>> Say in the lan, you have a dhcp server and a dns server.  your dhcp
>> clients (c1, c2 ,c3, ...)  booted up and get all the network
>> information from the dhcp server (ip, gateway, dns, ...).  Then from
>> another machine d1, you ping c1, and the dns returned c1 with the ip
>> address.
>>
>> question 1:  how dns server get that c1 information?   from dhcp server
>> or from dhcp client?
> 
>>From DNS configuration file, or from dynamic DNS.
> 
>>  dhcp update dns everytime it releases a dhcp client?, how dhcp to
>> update dns?
>>
> 
> I don't think dhcp ever does this, but I might be wrong. The client
> could
> update the DNS server using dynamic DNS.
> 
>> question 2:  when a user changed the name of c1 to cx without reboot
>> c1, (say changed c1's dhcpcd.conf, c1's hosts, etc).  then you ping cx
>> from d1 again, will you get cx's ip address from dns?, for the cases
>> you with or without restarting c1's eth0.
>>
> 
> Changing the /etc/dhcpd.conf file won't affect the client at all till
> the dhcp lease expires, and even then won't affect DNS unless the
> client updates DNS with the aforementioned dynamic DNS..
> 
> Daniel Feenberg
> feenberg is at nber dotte org
> 
>> Thanks
> 
> 

dhcp server has primary responsibility to insert/remove dns records as
required. Tailing logs on server show after offer dns exchanges.

Although there is client option in Windows to "register with dns" I
believe it is truly up to dhcp server to handle this. I think there are
settings to control whether client updates are allowed.

It took me several days to get ddns working...ended up getting hammered
over a missing period in name file. Only issues I have with it now are
frequency of updates and fact that it is clobbering my primary/static
domain file.