DNS Literacy Series 3: Smart DNS (BIND + VIEW)

DNS Literacy Series 3: Smart DNS (BIND + VIEW) preface: Smart DNS is the function implementation of BIND + VIEW. In China, the first thing we put smart DNS into the market was even (how can we feel unmodest ). I think the introduction of the VIEW function in BIND9.X is not targeted at China, but this function can solve the interconnection problem between network operators in China. This article is based on your experience in building and maintaining intelligent DNS over the past few years. The rush of time and limited knowledge will inevitably lead to errors. Let's discuss them one by one. The premise of www.2cto.com smart DNS: There is a premise for using smart DNS, that is, all network operators have their own public network DNS to provide domain name resolution services for their users. If this is not the case, there is no need for intelligent DNS (the reason will be discussed below ). Fortunately, the current situation basically meets this condition. China Netcom, China Telecom, and CERNET all have their own systems. Intelligent DNS: the most basic function of intelligent DNS is to intelligently identify the users who access your website, and then record your domain name (Domain Name) based on different visitors) it is parsed into different addresses. If the visitor is a Netcom user, the intelligent DNS server will resolve the IP address of the Netcom corresponding to your domain name to the visitor. If you are a telecom user, the smart DNS server will resolve the Telecom IP address corresponding to your domain name to this visitor. Therefore, we can allow users from China Netcom, China Telecom, CERNET, China Mobile, and abroad to access your server intelligently. The principle of smart DNS: Take ABC. COM domain name as an example. The process of accessing WWW. ABC. COM. The details irrelevant to the discussion in this article are omitted here, with the aim of simplifying the complexity.

1. The Netcom user requests the local DNS to parse WWW. ABC. COM. 2. The local DNS is directed to the authoritative DNS of ABC. COM (the authoritative DNS here must be intelligent DNS ). 3. Intelligent DNS matches the IP address of the requester (local DNS here) in its own ACL and returns the matching result to the local DNS. 4. The local DNS informs the user of the result and caches the result. 5. the user accesses the website server on the China Netcom line.
Intelligent DNS is particularly important: There are several important issues that should be listed separately. Otherwise, you will be surprised when using intelligent DNS. 1. Intelligent DNS determines the user source based on "Local DNS" instead of the user's own IP address. 2. Extend from top to bottom. If a telecom user uses Netcom DNS, the smart DNS will match the resolution result of Netcom. 3. local DNS generally does not request resolution from intelligent DNS in person, which is determined by the network topology of the local DNS. For details, see another post titled Literacy Series: public Network DNS http://www.bkjia.com/net/201210/161839.html www.2cto.com smart DNS problems: 1. it is difficult for network operators to collect IP addresses, such as the DNS used by small operators such as "Great Wall broadband" and "radio/TV network", which is not suitable for intelligent DNS at all. Therefore, intelligent DNS does not mean dividing operators into smaller ones as possible. In short, it is good to combine your own capabilities. 2. the penetration of various major network operators (Fortunately, it is an individual phenomenon, but it should be paid attention ), for example, Guangdong Telecom's Internet DNS backend has an unknown number of servers set up on the Netcom line. The consequence of this is that it is clearly the use of the Telecommunications DNS, but sometimes it is resolved to the results of the network. 3. As we all know, more and more network attack events are on the DNS, Which is helpless. Finally, I will not discuss the technical details about setting up intelligent DNS. I believe it is easy to find it online.