Abstract
The Domain Name System (DNS) is a naming system which transforms human readable domain names, into machine readable IP addresses and vice versa. The DNS servers create a database entry for each domain and send the equivalent IP address when they receive a query. DNS servers synchronize themselves with the authoritative DNS sources. When a query came to DNS server, it caches this request for future queries. If this request comes from a non-authentic client and has cached by DNS server, this causes a poisoned cache. This request may come from an improper software, a wrong configured name server or a malicious software which is created to exploit the DNS system.

Conventional DNS Query

Let’s explain this with an example. At first, the client makes a request for www.example.net to the IPS’s DNS server. The DNS server knows that this client is not an authoritative for the domain, so it also knows that it has to find it out of its cache, not in the local zone. Read more »