Date: Wed, 28 May 2008 08:32:17 -0400 From: Steve Bertrand <iaccounts@ibctech.ca> To: freebsd-net@freebsd.org Subject: Re: IPv6/IPv4 DNS resolver source Message-ID: <483D50D1.8000707@ibctech.ca> In-Reply-To: <m2wslfwpcp.wl%Jinmei_Tatuya@isc.org> References: <483B3E7F.8000907@ibctech.ca> <m2wslfwpcp.wl%Jinmei_Tatuya@isc.org>
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>> Is there anyone here who can advise me where in the source tree I would >> find the DNS resolver code that performs AAAA/A record lookups, and more >> specifically, the fallback to A lookup if AAAA fails? > > Assuming you're considering getaddrinfo(), see res_queryN() in > lib/libc/net/getaddrinfo.c. > > BTW: "fallback" does not really accurately describe the behavior. > When AF_UNPSEC is specified, both AAAA and A queries are issued, > whether or not the AAAA query fails. Thank you for the info. I did not know that little tidbit. I've got my first IPv6 DNS, mail, web etc server up and running now, and before I think about migrating the actual production network, I want to perform some extensive testing, all the while being familiar with the framework of the resolver itself, and how to overcome particular DNS/connectivity issues (if possible). ie: I want to learn more about how DNS and IP react in the event I lose my IPv6 BGP peers (or IPv4 peers), and also write in some debug log writing into the resolver if certain events trigger. Steve
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