One of the DNS Literacy Series: Internet DNS

One of the DNS Literacy Series: the Internet DNS public network DNS servers directly serve the majority of Internet users and are responsible for translation between domain names (Domain Name Records) and IP addresses. Internet DNS is usually used by various network operators to plan the DNS distribution based on their own network distribution. Generally, it is placed by administrative region, such as by province. Each province is also divided into different regions. Www.2cto.com over the past few years, careful netizens will find that when surfing the Internet, if a wrong URL address (or simply inexplicably) will access websites such as website 114 or Baidu. Today, I drew a simple chart to briefly explain the reasons.

The basic architecture of the Internet DNS Network is in the square frame, and the frontend hardware devices are responsible for receiving user resolution requests, as we often mention F5 (hardware devices have a single function and have a huge load capacity, therefore, it is suitable to use it as A front-end device, which is represented by A in the figure ). Frontend devices are connected to recursive server groups (generally LAN connections and WAN connections ). When a user requests domain name resolution, the front-end device will pass the request to its recursive DNS processing, and finally inform the user of the result. At the same time, front-end devices also have functions such as load balancing and link status check. Www.2cto.com in recent years, various network operators, such as China Netcom and China Telecom, have launched a network promotion service using DNS technology. The principle is very simple, that is, when users accidentally error the URL address or the domain name cannot be resolved for some reason (such as the domain name is in arrears, the front-end devices of Internet DNS will automatically resolve users to a promoted website to gain internet promotion revenue (shameless, not considering users' feelings at all ). If so, why don't we directly request domain name resolution from the recursive server group without bypassing the front-end devices? Well, the idea is good, but there are two difficulties here: www.2cto.com 1. The IP addresses of recursive DNS are not published, and you don't know, you can't use them. 2. The operator has restricted the IP Address requested from the recursive server and cannot use it !! Benefits: 1. Use foreign DNS. 2. Build your own recursive DNS.