DNS Resolution Principle and Linux Server Configuration Practice

This article introduces the principles, Linux configuration, and setup methods of DNS (Domain Name System). DNS, often referred to as the "phone book" of the Internet, translates domain names (e.g., baidu.com) into IP addresses, enabling domain-name-to-IP mapping. Its resolution process consists of six steps: local cache query (checking the hosts file), local DNS server query, root domain server query, top-level domain server query, authoritative domain server query, and finally returning the IP address to the operating system. In Linux, local DNS configuration is implemented through two key files: `/etc/hosts`, acting as a local "mini-address book" with the highest priority; and `/etc/resolv.conf`, which specifies DNS servers (e.g., 114.114.114.114), though it may be dynamically overwritten. Taking BIND as an example for DNS server setup, the steps include installing the software, configuring the main file `/etc/named.conf`, creating forward and reverse zone data files, starting the service, and testing. Common issues include configuration syntax errors, firewall blocking the 53 port (DNS default port), and inability for other devices to resolve names. Troubleshooting involves checking configurations, logs, and permissions. DNS is fundamental to network communication. Mastering its principles and configuration allows efficient management of domain name resolution services.