I. What is DNS

The Domain Name System (DNS) is a way to find machines on the Internet by name. Like one needs the address to go to a friend's house, a host on the Internet needs the IP address of another host to access it. But IP addresses are only numbers, which are hard to remember compared to names. So, the domain name system helps match names and IP addresses.

II. What is DNS Pollution

DNS cache pollution, or DNS cache poisoning, means that some data packets in domain name servers make domain names point to the wrong IP addresses. Usually, there are trustworthy domain name servers on the Internet, but to ease network traffic, normal domain name servers temporarily save the resolution records they get from higher domain name servers. When other machines ask to resolve domain names, they can give quick service. If a local domain name server's cache gets polluted, it will send computers in the domain to the wrong server or server address.

III. How to Deal with DNS Pollution Detected

1. One way to identify DNS contamination is when the website you visit does not match the expected one. You should quickly inform the network administrator about the situation. The network administrator will remove the contaminated DNS cache and carry out suitable next steps. 

2. Usually, legitimate websites use HTTPS encryption. When a domain name is taken over, the website will often show a certificate error warning. Please do not overlook the danger and keep visiting the website.