For this I followed the steps mentioned in https://apple.stackexchange.com/a/345539 in order to enable the AAAA records.

test@Tests-MacBook-Pro ~ % cat configureTunService
echo "Tun Service before configuring"
scutil <<EOF
open
d.init
show State:/Network/Service/utun4_tunnel/IPv6
quit
EOF

scutil <<EOF
open
d.init
d.add Addresses * a:b:c:d::1
d.add DestAddresses * a:b:c:d::1 ::
d.add Flags * 0 0
d.add InterfaceName utun4
d.add PrefixLength * 64
set State:/Network/Service/utun4_tunnel/IPv6
set Setup:/Network/Service/utun4_tunnel/IPv6
quit
EOF

echo "Tun Service after configuring"
scutil <<EOF
open
d.init
show State:/Network/Service/utun4_tunnel/IPv6
quit
EOF
test@Tests-MacBook-Pro ~ %

test@Tests-MacBook-Pro ~ % sudo ./configureTunService
Tun Service before configuring
  No such key
Tun Service after configuring
<dictionary> {
  Addresses : <array> {
    0 : a:b:c:d::1
  }
  DestAddresses : <array> {
    0 : a:b:c:d::1
    1 : ::
  }
  Flags : <array> {
    0 : 0
    1 : 0
  }
  InterfaceName : utun4
  PrefixLength : <array> {
    0 : 64
  }
}
test@Tests-MacBook-Pro ~ %


Above step worked and got AAAA records enabled for resolvers.



test@Tests-MacBook-Pro ~ % scutil --dns
DNS configuration

resolver #1
  nameserver[0] : 8.8.8.8
  if_index : 6 (en0)
  flags    : Request A records, Request AAAA records
  reach    : 0x00020002 (Reachable,Directly Reachable Address)

resolver #2
  domain   : local
  options  : mdns
  timeout  : 5
  flags    : Request A records, Request AAAA records
  reach    : 0x00000000 (Not Reachable)
  order    : 300000

.......

DNS configuration (for scoped queries)

resolver #1
  nameserver[0] : 8.8.8.8
  if_index : 6 (en0)
  flags    : Scoped, Request A records
  reach    : 0x00020002 (Reachable,Directly Reachable Address)

test@Tests-MacBook-Pro ~ %


After that as mentioned in https://superuser.com/a/86188 I updated the DNS settings with my DNS IPv6 ServerAddress, but it didn't seem to work for me.



test@Tests-MacBook-Pro ~ % cat getServiceId
scutil <<EOF | awk -F' : ' '/PrimaryService/ { print $2 }'
open
get State:/Network/Global/IPv4
d.show
quit
EOF
test@Tests-MacBook-Pro ~ %
test@Tests-MacBook-Pro ~ % cat modifyDns
PRIMARY_SERVICE=$(./getServiceId)
echo "primary service Id: ${PRIMARY_SERVICE}"
echo "DNS servers before modifying:"
scutil --dns | grep "nameserver"
scutil <<EOF
open
d.init
d.add ServerAddresses * aa:bb:cc:dd::1
set State:/Network/Service/${PRIMARY_SERVICE}/DNS
quit
EOF
echo "DNS servers after modifying:"
scutil --dns | grep "nameserver"
test@Tests-MacBook-Pro ~ %

test@Tests-MacBook-Pro ~ % sudo ./modifyDns
primary service Id: 1882E894-E43A-4885-8754-765FEF78B656
DNS servers before modifying:
  nameserver[0] : 8.8.8.8
  nameserver[0] : 8.8.8.8
DNS servers after modifying:
test@Tests-MacBook-Pro ~ %
test@Tests-MacBook-Pro ~ % scutil --dns
DNS configuration

resolver #1
  flags    : Request AAAA records
  reach    : 0x00000000 (Not Reachable)

resolver #2
  domain   : local
  options  : mdns
  timeout  : 5
  flags    : Request AAAA records
  reach    : 0x00000000 (Not Reachable)
  order    : 300000

......