DNS domain name hijacking, domain pollution

　　1. Basic principles of DNS
　　DNS Domain name system domain name system; the cornerstone of Internet communications is IP, but the IP number, not a good memory, so we use the domain name instead of IP makes it easier to remember; it must be genuine communication with IP carried out, so it is necessary to domain names into IP.
　　DNS Domain Name Service is a tree structure, a domain name is parsed from near their own domain name from a domain com / net / cn / ... to multi-level domain name, IP final resolution to
　　be responsible for building, maintaining the DNS server is operational providers, telecom operators, China mobile, Unicom, China Railcom, China Netcom, education network; especially small operators of domain name server is not very stable, sometimes domain name hijacking.
　　After the hijacking occurs using IIS7 website monitoring , enter your domain name check to see if there is a problem is not hijacked, pollution, the site linked to the black chain and the opening speed and other issues Jieke check with.
　　2. The domain name hijacking
　　the domain name server maintains a record of all domain names --IP when the domain name server receives a query request, will be in the cache, the database query corresponding record, and then returns the data to the client;
　　if someone ( hacker) maliciously modified the contents of the record, let the domain name resolves to the wrong IP address, then the domain name resolves to the wrong IP (there may be competitors of the page), which is the domain name hijacking.
　　3. the domain pollution
　　-user client computer send queries to the DNS domain name server, DNS server then queries the data back to the user for some time delay between, if hacker use this time to forge a dns result data back to the user,
　　that user gets resolved is wrong, this is called The domain pollution
　　4. GFW a "legitimate" domain pollution
　　GFW called Great Firewall of China: China's Internet content is automatically reviewed, filtration systems; such as foreign and domestic websites have always spread negative energy, we can make this site GFW domain name domain names pollution, so that the domain name resolution to a wrong ip, then this would not visit the natural site.