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PREFER_IPV4_ADDRESS is broken on IPv6-only hosts, as it causes busybox utilities (ping, traceroute, ntpd) to forcibly use the A record instead of the AAAA record when resolving a DNS name. This obviously fails when there is no IPv4 connectivity. Since IPv6-only hosts or routers will only become more common over time, disable PREFER_IPV4_ADDRESS to support this use-case. As a side-effect, disabling PREFER_IPV4_ADDRESS changes the default resolution behaviour of busybox utilities on dual-stack hosts. Busybox utilities now simply use the order given by getaddrinfo(), so they will now prefer IPv6 addresses when resolving a name with both A and AAAA records if there is IPv6 connectivity. This is in line with RFC 6724. PREFER_IPV4_ADDRESS was likely intended to work around naive implementations of getaddrinfo() that could return AAAA records first, even on an IPv4-only host. But both musl (since 1.1.3) and glibc correctly implement RFC 6724 for getaddrinfo() and check connectivity to determine the correct order in which to return records. On IPv4-only hosts, getaddrinfo() will return A records first, so there is no need for the PREFER_IPV4_ADDRESS hack. See also: https://bugs.busybox.net/show_bug.cgi?id=12381 Fixes: FS#84 Fixes: FS#2608 References: https://github.com/openwrt/openwrt/pull/4167 Signed-off-by: Alexander Traud <pabstraud@compuserve.com> Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org> (cherry picked from commit 7fea9d9f5dd282a7049d77cc6b75e0a703ead26c)