From: Nigel Gilbert <n.gilbert@...>
Date: 2003-06-20T01:57:23+09:00
Subject: Summary: TCP/IP protocol and Net::HTTP

Thanks to all who have run trials and especially to Guy Decoux who 
referenced an earlier discussion in ruby-talk that shed light on the 
problem (which was: Net::HTTP.get_print 'ad.doubleclick.net', '/' times 
out under MacOSX, but not on other platforms).  My summary is:

On MacOSX, the implementation of getaddrinfo (which is used to 
translate 'ad.doubleclick.net' into an IP address) starts by sending a 
query to the doubleclick DNS server using an IPv6 format.  This DNS 
server should either respond with the desired IP address, or decline to 
do so.  In fact, the doubleclick DNS server makes no response at all, 
and the Mac keeps waiting until eventually it times out.

This explains why the problem only seems to occur only with the 
combination of (a) doubleclick [their DNS server is unusual [1] in that 
  it doesn't respond) and (b) MacOS X (this implementation of 
getaddrinfo first tries an IPv6 format, and then backs down to an IPv4 
format query, while other ruby implementations don't attempt an IPv6 
query at all).

The work around (not yet tried) is to rebuild ruby with the configure 
options:

           --enable-ipv6 \
           --with-lookup-order-hack=INET

which essentially says try IPv4 before IPv6

The earlier ruby-talk thread related to all this starts at 66245

I hope that the above options could become the default in the next 
release.

Nigel

[1] Or perhaps one could say, 'buggy'


On Thursday, June 19, 2003, at 05:33 PM, Michael Campbell wrote:

> --- Jim Menard <jimm@io.com> wrote:
>> Nigel Gilbert <n.gilbert@soc.surrey.ac.uk> writes:
>>
>>> If there is someone out there using MacOSX, could you try it and
>> see
>>> whether this theory is correct?  What you need to do is:
>>
>> I just tried under OS X and see the same timeout problem.
>
> As Guy mentioned, this is a doubleclick issue; they're not responding
> to AAAA (ipv6?) requests, which is what Ruby is issuing.
>
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