dhcp client and dns bind question

[feenberg at gmail.com]

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