The fixed-address parameter, a hostname or an IP Address?

[Simon Hobson]

Juan Antonio García Moreno <jagarcia at emergya.com> wrote:

> I have inherited a network installation that has a ISC DHCP Server and a Bind9.

Always fun inheriting something like that.

> When I have saw the DHCP config file (dhcpd.conf), I have missed because the host definitions are as follow:
> 
> host pc-user-01 {
>    hardware ethernet fa:ba:da:26:bb:5a;
>    fixed-address pc-user-01.dominio.com;
> }
> 
> And on the DNS config file are the IP Address definition as follow:
> 
> Direct resolution -->        pc-user-01   A    192.168.100.100
> Reverse resolution --> 100   IN   PTR   pc-user-01.dominio.com.
> 
> I everytime have configured the host definition as follow:
> 
> host pc-user-01 {
>    hardware ethernet fa:ba:da:26:bb:5a;
>    fixed-address 192.168.100.100;
> }
> 
> I have searched information about this way to configure the host definition and I haven't found nothing about to configure a name in the fixed-address parameter instead an IP Address.
> 
> Is this way to configure the host definition correct?

Either way is correct. If you use a name then it will be resolved at daemon startup time.


> Where is the documentation that explain this?

You need to be looking at man "dhcpd.conf". I find the following bits that are relevant :

> As you can see in Figure 2, you can specify host addresses in parameters using their domain names rather  than their  numeric  IP  addresses.


The fixed-address declaration
...
> Each address in the fixed-address declaration should be either an IP address or a domain name that resolves to one or more IP addresses.