Hackercombat.com Presents: A Crash Course of DNS Cache Poisoning. It is unfortunate that there are still DNS services that are still vulnerable to DNS cache poisoning attack. In DNS, a 16-bit identifier ID is prepared in DNS message. This is used to determine which query message it is for when it receives a response message. If the ID in the inquiry does not match the ID included in the response packet, the cache server processes the same as the ID as the corresponding response.”]
Source: https://hackercombat.com/hackercombat-com-presents-a-crash-course-of-dns-cache-poisoning/