building a DNS system

[Sten Carlsen]

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Stephane Bortzmeyer wrote:
> On Wed, Jul 19, 2006 at 02:47:28PM +0200,
>  Sten Carlsen <ccc2716 at vip.cybercity.dk> wrote 
>  a message of 23 lines which said:
>
>   
>> What times should we expect for loading all those images?
>>     
>
> It depends on:
>
> * wether you pick the first address (which does not work) or the
> second (which does work). Pure luck. "dig A broken.bortzmeyer.fr".
>   
I don't know what happened in this case, I was too lazy to start packet
sniffing.
> * how your network infrastructure reports that the first address is
> not reachable (immediate ICMP "Network unreachable" or black
> hole?). 
>   
No special effort has been done on my part. I run a Redhat 9.0 as NAT
and firewall (blocking all private IPs 10., 172., 192., nothing else),
wget when given the bogon IP, not the address will hang forever. Could
be interesting to know why wget takes the good address 4 out of 4 times.
Ping(bogon IP) does not get the message, just pings away until
interrupted, 100% packet loss.

Ping broken.bor...fr will consistently go to the good address, why?
Somehow this experiment is not showing realistic results at my place.

Maybe something else should be done to get a realistic feel for the case.
> * how your browser reacts to this unreachability.
>
> The purpose of this little experiment is to see wether a pure DNS
> redundancy solution is realistic for HTTP (I do not think so).
>   
Output from wget. It will consistently show this:

silver:~>wget -S broken.bortzmeyer.fr
--15:13:02--  http://broken.bortzmeyer.fr/
           => `index.html.3'
Resolving broken.bortzmeyer.fr... done.
Connecting to broken.bortzmeyer.fr[80.67.170.53]:80... connected.
HTTP request sent, awaiting response...
 1 HTTP/1.1 200 OK
 2 Date: Wed, 19 Jul 2006 13:13:02 GMT
 3 Server: Apache/2.0.54 (Debian GNU/Linux) DAV/2 SVN/1.1.4
mod_python/3.1.3 Python/2.3.5
 4 Cache-Control: no-cache
 5 Connection: close
 6 Content-Type: text/html

    [ <=>                                 ] 2,067         
1.97M/s            

15:13:03 (1.97 MB/s) - `index.html.3' saved [2067]


-- 
Best regards

Sten Carlsen

Let HIM who has an empty INBOX send the first mail.