Dynamic DNS: Ubuntu vs. CentOS.

[Shawn O'Shea]

On Mon, Jul 4, 2011 at 9:55 PM, Ken D'Ambrosio <ken at jots.org> wrote:

> Hey, all.  At my new employer -- where I have essentially zero visibility
> into how DNS is run -- my Ubuntu boxen push out forward-lookup DNS just
> fine, but not so much my CentOS box (at least, with default
> configurations).  Ideas on what I need to do to rectify this?
>
>
Many DHCP+DNS networks set a DNS name when they hand out DHCP addresses even
if you aren't using a DHCP implementation that supports Dynamic DNS
extensions (ie Microsoft DHCP+DNS can be made to do this, Infoblox
appliances do this). As far as I know, the implementation in CentOS 5 does
not do this (although I do believe that newer open source DHCP clients can
do DDNS, hence why your Ubuntu works). Some DHCP/DNS implementation just
need you to tell them what your hostname is (no DDNS required) like some
cable operators will not hand out a DHCP lease unless you send the hostname
in the DHCP request.

If DDNS isn't the issue, then you may just need to tell CentOS DHCP client
to send it's hostname (which it does not do by default). If your ethernet
interface is eth0 and your CentOS boxes name is "foobar", then create a file
with your favorite editor (as root), /etc/dhclient-eth0.conf and add the
line: send host-name "foobar";  (note the semi-colon at the end of the line)
and restart networking (again as root) /sbin/service network restart

Otherwise you might need to look into whether the DHCP client in 5.6 can do
DDNS.

-Shawn
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