Q of Forwarders Statement

Hideaki NISHIMURA nishimura at mxb.nes.nec.co.jp
Tue Oct 11 12:11:10 UTC 2005


Thanks to your follow up, Kevin. :-)

I understood I could also use forward/forwarders statement
for a stub zone.

Finally, I understood I could use it for any type zones
except a hint zone and a delegation-only zone.

I gave the bind-9.3.1 source code a once-over. However,
there is not cofidence whether what I confirmed is right.

Best regards.
#And I'm sorry in clumsy English.


  | Hideaki NISHIMURA wrote:
  | 
  | >Thanks, Kevin. :-)
  | >
  | >I understand the ARM's syntax miss of forwawrders statement
  | >(we can use empty list).
  | >
  | >And your notice about behavior of forwarding in master zone
  | >is very useful.
  | >
  | >There is subzones (ex. qux.foo.bar.co.jp) in the lower part
  | >of foo.bar.co.jp zone.  So that, I think it is right to use
  | >forwarders statement with empty list in master zone.
  | >
  | >And now, I was able to know forwarders statement could use
  | >not only in master zone (or slave zone) but also in forward
  | >zone.  
  | >
  | You can use it for a stub zone too.
  | 
  | - Kevin
  | 
  | >
  | >Best regards.
  | >
  | >
  | >  | 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
  | >
  | >--------
  | >Hideaki NISHIMURA (^_^)

--------
Hideaki NISHIMURA (^_^)



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