why am I seeing update denied in Bind9 logs for dhcp clients ?

Simon Hobson dhcp1 at thehobsons.co.uk
Fri Mar 2 11:35:26 UTC 2012

Gregory Machin wrote:

>I have a ddns configuration with the dhcpd server writing dhcp clients
>hostname and ip to the bind9 dns server. But i'm seeing a lot of
>dhcp clients trying to writing into zones

Windows clients by any chance ?

>        zone "69.168.192.in-addr.arpa" {
>        type master;
>                file "/var/lib/bind/192.168.69.interenal.rev";
>                update-policy { grant dhcp-server-key subdomain
>69.168.192.in-addr.arpa. ANY;
>                                      grant * self * A TXT;
>                                };
>                };

All I have is :
zone "0.168.192.in-addr.arpa" in {
         allow-update { key DHCP_UPDATER ; };
         file "192.168.0";
         type master;

Default on Windows clients is for the client to attempt to update the 
DNS - because "that's the way MS does it". You need to add "deny 
client-updates" (I think, check the man page) to your DHCP config for 
it to ignore clients requests to do their own updates.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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