Public DNS - recursion no - Access to the Internet

[Andy Shellam (Mailing Lists)]

Pascal Hambourg wrote:
> This is not what I observed on a Debian GNU/Linux system. When 
> resolv.conf contains "nameserver 0.0.0.0" or no nameserver entry or does 
> not exist, DNS queries are sent to 127.0.0.1, with source address 
> 127.0.0.1. So it does not seem that the resolver seeks any local 
> addresses on "real" network interfaces. My understanding is that 
> "nameserver 0.0.0.0" is invalid and ignored. In this case, 127.0.0.1 is 
> used as the default nameserver, as stated by the resolv.conf manpage : 
> "If no nameserver entries are present, the default is to use the name 
> server on the local machine". Other OSes may behave differently.
>   

I observed that on a Redhat system, it transparently rewrites 0.0.0.0 to 
127.0.0.1, however whether this is in the network stack or not I'm not 
sure - it could just be individual applications, hence it's another 
"point of failure" to remove when diagnosing problem like the OP had 
when this thread started.

*BSD and Windows, report "invalid address" when 0.0.0.0 is used.  
Personally I think if you mean the localhost, you should put the proper 
localhost address which is anything in the 127.0.0.0/8 subnet (commonly 
127.0.0.1.)