default local DNS caching name server

[Chuck Anderson]

On Sat, Apr 12, 2014 at 01:22:32PM +0800, P J P wrote:
> > On Saturday, 12 April 2014 7:38 AM, Simo Sorce wrote:
> > Not true, in many networks you want it, for example in corporate
> > networks. You really want to be able to resolve the local resources and
> > they are only resolvable if you consult the local DNS as provided to you
> > by DHCP.
> 
>   True. The local resolver can be configured to resolve internal domains by pointing it to the dynamic name servers. Also one can set 'DNS1=127.0.0.1' in /etc/sysconfig script, that way dynamic name servers are listed as DNS2, DNS3 etc.
> 
> For this very reason the dynamic name server entries need to go as "..transitory name servers to be used by the trusted local resolver".

You cannot rely on DNS2 and DNS3 to be queried UNLESS DNS1=127.0.0.1
fails to respond.  This might be a way to mitigate failure of the
local caching resolver process, but it is not a way to ensure the
ability to resolve internal names from the corporate nameserver.  The
way to ensure the latter is to configure the local caching resolver to
forward to the DHCP-provided nameservers rather than becoming a full
iterative resolver.