Updating forwarders dynamically

[Jim Reid]

>>>>> ">A" == A Farber <Alexander.Farber at t-online.de> writes:

    A> Hi, I'm using OpenBSD -current with bind 9.3.0 and I receive
    A> the nameservers from my ADSL-provider when I connect to it
    A> using ppp. I've searched this newsgroup and have learnt that
    A> forwarding is unneeded in my setup and I should just use the
    A> root hints.

Correct. 

    A> But still I'm curious, if there is a way to update the
    A> "forwarders" option in the snippet of my named.conf
    A> (s. below)dynamically, via nsupdate or maybe Net::DNS and not
    A> through generating the named.conf file anew and restarting the
    A> named?

Forwarding is never the answer. Repeat the previous sentence until you
understand it. :-) Consult the list archives for details.

Tools like nsupdate and the perl Net::DNS library use the DNS protocol
to change the content of zones. They cannot change the content of name
server configuration files. There's no documented protocol to do that.
So as the reference DNS implementation, BIND provides no mechanism for
changing a name server configuration over the wire. Enterprise DNS
solutions can support on-the-fly reconfiguration of the name servers.
That's typically done by some proprietary software diddling the
back-end database that holds the server configurations.

BTW, it's not mandatory to kill and restart the name server after
named.conf changes. An 'rndc reconfig' is usually sufficient. Unless
the server is running as a non-privileged user and needs to do some
privileged operation like binding to port 53 on a new interface.
Restarting a name server should only be necessary when the software is
changed.