Q of Forwarders Statement

[Kevin Darcy]

Hideaki NISHIMURA wrote:

>Hello, bind-users.
>
>I have two questions about forwarder function (bind-9.3.1).
>
>first, I set up the forwarders zone as follows (summary).
>
>    --------------------------------------------------------
>    options {
>       ...
>       forward only;
>       forwarders { 192.168.5.1; 172.16.5.1; };
>       ...
>    };
>
>    zone "foo.bar.co.jp" {
>       type master;
>       file "db.foo.bar.co.jp";
>       forward only;
>       forwarders {};
>    };
>    --------------------------------------------------------
>
>  Generally, "forward" and "forwarders" statement use with
>  "forward" zone type.
>
>  But, I want to set up "no forward" in foo.bar.co.jp zone.
>  So that, I am setting up these statement with "master"
>  zone type.
>
>  Is this configuration is correct ?
>
>Second, I read the explanation of zone statement. 
>(Bind 9 ARM distributed with bind-9.3.1).
>
>  In "6.2.23 zone Statement Grammar" section:
>
>    --------------------------------------------------------
>    Zone zone_name [class] [{
>      ...
>      [ forward (only|first) ; ]
>      [ forwarders { ip_addr [port ip_port] ; [ ip_addr [port ip_port] ; ... ] }; ]
>      ...
>    }];
>    --------------------------------------------------------
>
>    This description means forwarders statement needs a
>    least one option ("forwarders { X.X.X.X; };").
>
>  But, in "6.2.24.1 Zone Types" section, "forward" paragraph:
>
>    --------------------------------------------------------
>    If no forwarders statement is present
>      or an empty list for forwarders is given, ...
>    --------------------------------------------------------
>
>    This description means it arrows "forwarders {};".
>
>  Which is correct ? (arrows least one or empty)
>
>Best regards.
>  
>
The ARM syntax is wrong. An empty forwarders statement is valid.

Note, however, that an empty forwarders won't prevent forwarding for the 
foo.bar.co.jp zone, since there is no forwarding for that zone anyway -- 
you're serving it as a master zone, so all of the responses will come 
from your own authoritative data. The only effect of the empty 
forwarders is to disable forwarding for *subzones* of foo.bar.co.jp. If 
you have no subzones of that zone, then there is no need for the empty 
forwarders.

- Kevin