IPAddr#reverse

# File tmp/rubies/ruby-3.4.1/lib/ipaddr.rb, line 389
def reverse
  case @family
  when Socket::AF_INET
    return _reverse + ".in-addr.arpa"
  when Socket::AF_INET6
    return ip6_arpa
  else
    raise AddressFamilyError, "unsupported address family"
  end
end