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Why can I see AAAA DNS requests when I run tcpdump on my Scientific Linux PC when I haven't got any IPv6 addresses? I already rebooted after setting NETWORKING_IPV6=no in /etc/sysconfig/network and options ipv6 disable=1 in /etc/modprobe.d/ipv6.conf, but I can still see AAAA requests if I visit a few websites. How can I disable the requesting of AAAA records?

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options ipv6 off and then in super shell run modprobe -r ipv6 – Nikhil Mulley Dec 21 '11 at 6:18
If you have an IPv4 address, you automatically have a 6to4 IPv6 address, through which you may be able to reach IPv6 hosts (depending on what IPv6 connectivity your ISP offers). – Gilles Dec 21 '11 at 23:42
Have you removed ::1 and other ipv6 addresses from your /etc/hosts? – Marcin Dec 22 '11 at 15:16
Firefox has additionally the option to disable IPV6: go to about:config then change network.dns.disableIPv6 – jofel Jul 19 '12 at 14:46
As per serverfault.com/questions/632665/how-to-disable-aaaa-lookups, there seems to be no easy way. – tuomassalo Mar 9 at 9:42

Check if file /etc/resolv.conf has "options inet6". If so, that line should be removed using your favorite editor (invoked via sudo or as root, after making a backup copy). If you are using DHCP, it may get put back in the next time you reboot even if you have no IPv6 in your kernel network stack.

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Try to pass the following option to the kernel, on the Grub stage:


Where modname is the module name of ipv6 on Scientific Linux (probably ipv6)

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