[X4U] Re: Leopard Issues - Some Responses

[John Douglass - User]

On Dec 4, 2007, at 3:13 PM, Stroller wrote:
>
> Yes, but YOU'RE not reporting the domain guessing problem (if I'm  
> reading your message of 3 December 2007 20:07:50 GMT correctly then  
> you explicitly state the opposite).

Agreed.  However, my domain guessing is working, but my DNS lookup  
using `host jr` does not, which of course was the point I was trying  
to make:  DNS client lookups and domain guessing are completely  
different beasts.  (See previous reference to Mozilla's explanation).

> My request for the results of `host jr` was for Jon Warms, although  
> Mr Forster's reply (4 December 2007 20:05:36 GMT) appears to prove  
> me wrong. I'd like to see it performed from within Verizon's network  
> to be sure.


Actually, I think Mr. Forster's reply proves you RIGHT, Verizon's DNS  
server should be returning NXDOMAIN but instead returns NOERROR.    As  
a friend of mine says, we might be in "violent agreement."

A simple way to see what happens is to open the terminal and issue  
"sudo tcpdump -n port 53" from the command line.  Then type in the  
"jr" into the URL box and see what happens.

What you should see is something like:

15:56:25.460883 IP 192.168.2.2.49857 > nameserver.domain: 46418+ A?  
jr.search1.
15:56:25.461500 IP nameserver.domain > 192.168.2.2.49857: 46418  
NXDomain* 0/1/0
15:56:25.461839 IP 192.168.2.2.49858 > nameserver.domain: 49011+ A?  
jr.search2.
15:56:25.462453 IP nameserver.domain > 192.168.2.2: 49011 NXDomain*  
0/1/0
15:56:25.603464 IP 192.168.2.2.49862 > nameserver.domain: 7689+ A? www.jr.com 
.
15:56:25.796455 IP nameserver.domain > 192.168.2.2.49862: 7689 1/5/3 A  
4.71.184.155

(names changed to protect the innocent).

Do the same thing under `host` and you will not get the final line,  
because the domain guessing is browser related not DNS client related.

Anyway, the results show my request first tacking on the first search  
domain listed in my DNS settings, then the second, and then finally  
doing domain guessing by sending "www.jr.com".   I postulate, based  
upon Mr Forster's reply,  that the NXDOMAIN above won't be there,  
instead the people experiencing problems will see NOERROR.  Thus you  
will not see the domain guessing portion.  I don't think this problem  
is caused by Leopard.  I can concede the possibility there might have  
been changes in the client resolver library code that would change the  
default behavior from Tiger to Leopard regarding the handling of a  
NOERROR return.  Either way the correct DNS server response (NXDOMAIN)  
would allow Leopard to behave as expected, because after all "jr" (in  
my case jr.searchdomain) doesn't exist, and the DNS should return an  
error.

-- John