BIND 9.7 : filter-aaaa-on-v4 option

BIND :  filter-aaaa-on-v4 option

[ What’s filter-aaaa-on-v4 options ? ]

This option filters AAAA records out from IPv4 to prevent frequently occurring IPv4 fallback due to IPv6 timeout configured wrongly

[ how to use filter-aaaa-on-v4 ]

This option is added BIND9.7.0b2 and later versions.
You need to compile BIND with ./configure --enable-filter-aaaa

root@ubuntu-7:~/bind-9.7.3# ./configure --help | grep aaaa  --enable-filter-aaaa    enable filtering of AAAA records over IPv4

compile BIND

2020  ./configure --enable-filter-aaaa 2021  make 2022  make install

named.conf

options {        directory "/var/cache/bind";        max-cache-size 1M;        recursion yes;        filter-aaaa-on-v4 yes; };

[ when AAAA queries come from IPv4 ]

AAAA recoreds are filterd out.
So IPv6 timeout won’t happen.

root@ubuntu-7:~# dig @127.1 www.isc.org aaaa ; <<>> DiG 9.7.3 <<>> @127.1 www.isc.org aaaa ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59145 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 1 ;; QUESTION SECTION: ;www.isc.org. IN AAAA ;; AUTHORITY SECTION: isc.org. 43168 IN NS sfba.sns-pb.isc.org. isc.org. 43168 IN NS ams.sns-pb.isc.org. isc.org. 43168 IN NS ord.sns-pb.isc.org. isc.org. 43168 IN NS ns.isc.afilias-nst.info. ;; ADDITIONAL SECTION: ns.isc.afilias-nst.info. 86369 IN A 199.254.63.254

[ when AAAA queries come from IPv6 ]

get AAAA records

root@ubuntu-7:~# dig @::1 www.isc.org aaaa ; <<>> DiG 9.7.3 <<>> @::1 www.isc.org aaaa ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50213 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 2 ;; QUESTION SECTION: ;www.isc.org. IN AAAA ;; ANSWER SECTION: www.isc.org. 557 IN AAAA 2001:4f8:0:2::d ;; AUTHORITY SECTION: isc.org. 43157 IN NS ams.sns-pb.isc.org. isc.org. 43157 IN NS ns.isc.afilias-nst.info. isc.org. 43157 IN NS sfba.sns-pb.isc.org. isc.org. 43157 IN NS ord.sns-pb.isc.org. ;; ADDITIONAL SECTION: ns.isc.afilias-nst.info. 86358 IN A 199.254.63.254 ns.isc.afilias-nst.info. 86358 IN AAAA 2001:500:2c::254