DDNS with host declarations

[Simon Hobson]

Jan Engelhardt wrote:

>when dhcpd.conf contains a host declaration, such as
>
>   host foobar {
>       fixed-address 192.168.234.2;
>       hardware ethernet 00:aa:bb:cc:dd:ee;
>   }
>
>then no DDNS update takes place at all. How can I achieve that
>
>   (a) DDNS updates are made, according to a fixed hostname (set in
>   dhcpd.conf)

'man dhcpd.conf' - look for update-static-leases


>   (b) DDNS updates are made, according to the preferred hostname
>   a client sent (in case it sent one)

I would think "ddns-hostname = <something>" where <something> is an 
expression to get the client supplied hostname. However, since 
clients might not supply a hostname, you probably also need to use a 
pick-first-value to use the client supplied hostname if there is one, 
or the statically defined one if it doesn't.

Be aware that in either case, the dhcp server will do a DNS update 
for every lease renewal (because it doesn't have a lease structure to 
track it with), and it will not delete the record when the lease 
expires.

My personal preference is to manually configure the dns when 
configuring static host declarations - or it's something you could 
script using nsupdate (or similar) if you are machine generating your 
configs.