ar@cello ~ % ping -4c1 a.root-servers.net.; ping -6c1 a.root-servers.net. PING a.root-servers.net (198.41.0.4) 56(84) bytes of data. 64 bytes from a.root-servers.net (198.41.0.4): icmp_seq=1 ttl=53 time=47.2 ms --- a.root-servers.net ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 47.160/47.160/47.160/0.000 ms PING a.root-servers.net.(a.root-servers.net (2001:503:ba3e::2:30)) 56 data bytes 64 bytes from a.root-servers.net (2001:503:ba3e::2:30): icmp_seq=1 ttl=56 time=66.2 ms --- a.root-servers.net. ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 66.156/66.156/66.156/0.000 ms ar@cello ~ % ar@cello ~ % zsh -c ' fqdn=oboe.murbly.net echo -n A: ; host -t A $fqdn echo -n AAAA: ; host -t AAAA $fqdn echo sorry for $SHELL syntax btw; integer succ=0 integer fail=0 integer mixed=0 integer samplesz=100 repeat $samplesz; do host oboe.murbly.net >/tmp/yy grep -q IPv6 /tmp/yy && ! grep -q NXDOMAIN /tmp/yy && (( succ++ )) ! grep -q IPv6 /tmp/yy && grep -q NXDOMAIN /tmp/yy && (( fail++ )) grep -q IPv6 /tmp/yy && grep -q NXDOMAIN /tmp/yy && (( mixed++ )) done; echo "Out of $samplesz attempts: $succ desired outcomes, $fail shitty outcomes, $mixed mixed outcomes" ' A:oboe.murbly.net has no A record AAAA:oboe.murbly.net has IPv6 address 2a00:f480:8:d::b0e:0 sorry for /usr/bin/zsh syntax btw Out of 100 attempts: 73 desired outcomes, 18 shitty outcomes, 9 mixed outcomes ar@cello ~ %