Checks a DNS server for the predictable-TXID DNS recursion vulnerability. Predictable TXID values can make a DNS server vulnerable to cache poisoning attacks (see CVE-2008-1447). The script works by querying txidtest.dns-oarc.net (see https://www.dns- oarc.net/oarc/services/txidtest). Be aware that any targets against which this script is run will be sent to and potentially recorded by one or more DNS servers and the txidtest server. In addition your IP address will be sent along with the txidtest query to the DNS server running on the target.