Linux Note 17 uses Bind to provide domain name resolution services.
DNS domain name resolution service
In order to reduce the threshold for users to access network resources, DNS (Domain Name System, Domain name system) technology arises at the historic moment. This is a technology used to manage and resolve the correspondence between domain names and IP addresses. To put it simply, it is able to accept the domain name or IP address entered by the user, and then automatically find the IP address or domain name that matches (or has a mapping relationship), that is, the domain name is resolved to IP address (forward resolution), or the IP address is resolved to domain name (reverse resolution). In this way, we only need to enter the domain name in the browser to open the website we want to visit. The forward resolution of DNS domain name resolution technology is also one of the most commonly used working modes.
As an important part of the Internet infrastructure, DNS technology provides the following three types of servers in order to provide uninterrupted, stable and fast domain name query services for Internet users and ensure the normal operation of the Internet.
Master server: it is unique in a specific area and is responsible for maintaining the corresponding relationship between domain names and IP addresses in that area.
Slave server: obtain the corresponding relationship between domain name and IP address from the master server and maintain it to prevent the master server from downtime.
Cache server: obtain the corresponding relationship between domain name and IP address by querying other domain name resolution servers, and save the frequently queried domain name information locally to the server, so as to improve the efficiency of repeated query.
