You can use the dig utility to see if a DNS server is recursive. Just do the scan in two steps. One major port scan using masscan, netscan, etc., then a smaller

You can use the dig utility to see if a DNS server is recursive. Just do the scan in two steps. One major port scan using masscan, netscan, etc., then a smaller scan of the IPs with port 53 open to see if they are recursive or not. You'll see this in dig's output if the server is not recursive: ;; WARNING: recursion requested but not available