DNS Cache Poisoning

From Hakipedia

DNS cache poisoning is a maliciously created or unintended situation that provides data to a Domain Name Server that did not originate from authoritative DNS sources. This can happen through improper software design, misconfiguration of name servers, and maliciously designed scenarios exploiting the traditionally open-architecture of the DNS system. Once a DNS server has received such non-authentic data and caches it for future performance increase, it is considered poisoned, supplying the non-authentic data to the clients of the server.