[dns-operations] To A or to AAAA - was Re: Signaling client

[Mark Andrews]

In message <20110119143850.91B418F1AF9 at drugs.dv.isc.org>, Mark Andrews writes:
> 
> In message <alpine.LSU.2.00.1101191342230.5244 at hermes-1.csi.cam.ac.uk>, Tony 
> Finch writes:
> > On Wed, 19 Jan 2011, Mark Andrews wrote:
> > >
> > > getaddrinfo() isn't the problem.  The problems happen after getaddrinfo.
> > 
> > Yes, you are right in principle.
> > 
> > I mentioned getaddrinfo itself because it also needs to be hardened
> > against IPv6-related failures, specifically timeouts in AAAA lookups when
> > A lookups succeed. If you can overlap the execution of getaddrinfo and the
> > subsequent connect()s then you can connect to an IPv4 address
> > quickly even if IPv6 is subject to either DNS or network level breakage or
> > slowness.
> 
> 99.999% of AAAA lookups work fine.  There are a few load balancers
> which are broken or mis-configured, much less than there were 5
> years ago.
> 
> > > I have slow start example code for all three of these methods which just
> > > replaces the loop over the results of getaddrinfo().
> > 
> > Sounds nice! Is it published anywhere?
> 
> I intend to soon.

And it can be found here:
http://www.isc.org/community/blog/201101/how-to-connect-to-a-multi-homed-server-over-tcp
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org