The Design and Research of Smart DNS Applied in ISP

DNS is the “nervous system” and “navigator” of the whole internet. It’s necessary to optimize traditional DNS’s system structure, resource location, mapping efficiency and security in the application of ISP environment because of traditional DNS system’s flaw by natural. The author first analysis the technical mechanism of the traditional DNS system, then optimize the structure, technique flow, protocol and security of the traditional DNS system considering the practical application demand of the DNS system in the ISP, at last the author construct the integrated proposal of the ISP Smart-DNS system. The ISP Smart-DNS system divide the traditional DNS system into forward-DNS module and backward-DNS module according to the different function of cacher query and recursive query; the forward-DNS module possess the function of domain-name’s pre-operation, realizing the elusion or redirection of the mistaken DNS request, the forbidden website’s DNS request and other ISP user’s DNS request; the backward-DNS module have the function of resource location which guide ISP users to the IDC belong to this ISP itself; the backward-DNS module have the function of TTL flag optimization which can optimize the A-record lifecycle in cache according to the times that domain name was requested, this function raise DNS system’s efficiency; the backward-DNS module also have the function of TC flag optimization which can avoid the DNS request based on TCP connection, this function not only raise DNS system’s efficiency, but avoid any network attack which is based on TCP.