From: Eric Hodel <drbrain@...7.net>
Date: 2005-09-20T08:49:39+09:00
Subject: Re: nslookup/config question

On 19 Sep 2005, at 13:26, Frank Goodman wrote:

> Apologies in advance if this is the wrong place to post, appreciate  
> any
> pointers to the right place if I've polluted the wrong thread
>
> Specifics:
>   ruby 1.8.2 (2004-12-25) [i686-linux]
>   Host: Linux gentoo 2.6.12
>
> My linux box does not run a nameserver, as it is a home machine  
> that I use
> for development. I connect to the internet through a Dlink router and
> cable-modem.
>
> When I do a Socket/TCPSocket.gethostbyname call from within ruby, for
> "unknown" hosts it returns an array that corresponds to my DynDNS  
> domain name
> with my "public IP address"
>
> When I run `nslookup` it returns:
>
> ** server can't find foo.foobar.frt: NXDOMAIN
>
> With the socket version it is more complicated for me to determine  
> bad hosts
> and I certainly can't do it in a portable way, so I'd like to set  
> things up so
> the Ruby.Socket code returns a proper error.
>
> I'm guessing this has something to do with my (improper)  
> configuration of my
> system or router. Any help would be appreciated
>
> I am curious why I would get different behaviours from the Ruby  
> gethostbyname
> and nsslookup which I would imagine should resolve down to a  
> gethostbyname
> call as well.
>
> Ideas?

I don't think this is a ruby issue...

$ nslookup foo.foobar.frt
Server:         192.168.1.15
Address:        192.168.1.15#53

** server can't find foo.foobar.frt: NXDOMAIN

$ ruby -rsocket -e 'Socket.gethostbyname("foo.foobar.frt")'
-e:1:in `gethostbyname': getaddrinfo: hostname nor servname provided,  
or not known (SocketError)
         from -e:1

Ruby uses the libc resolver to look up domain names.  (I forget if  
nslookup uses libc or its own builtin resolver... host does under OS X.)

Try also the pure-ruby DNS resolver:

$ ruby -rresolv -e 'p Resolv.getaddress("foo.foobar.frt")'
/usr/local/lib/ruby/1.8/resolv.rb:89:in `getaddress': no address for  
foo.foobar.frt (Resolv::ResolvError)
         from /usr/local/lib/ruby/1.8/resolv.rb:39:in `getaddress'
         from -e:1


-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
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