Abstract: Disclosed is a method for alerting on incorrect DNS records returned by DNS servers over the internet and related to data transfer associated with given one or more hosts. The method comprising the steps of: I. acquiring a reference association list comprising an association between a query list comprising DNS queries for corresponding DNS records related to said data transfer, and expected query response per each query in the query list. II. Acquiring a DNS server list comprising identifications of as many deemed reliable DNS servers as possible over the internet that may affect said data transfer; III. Scrutinizing the DNS servers in the list by repeatedly sending them the queries included in the query list. IV. Comparing each query response with the expected results so as to detect incorrectly responding DNS servers. V. Issuing an alert upon detecting an incorrectly responding DNS server.