dns

What is DNS, How it Works + Vulnerabilities https://www.cloudflare.com/learning/dns/what-is-dns/

what is DNS?

GetIPWith(domain)

how dns work?

1. DNS recursive resolver(本地，递归):负责实际的查询过程: 运营商(电信，联通)，某些云服务商(谷歌)

2. 查询过程: 按照层级，自高向低查询(域名自右向左)；

   1. root nameserver(根域名服务器,指向顶级域名)
   2. top level nameserver(顶级域名服务器 cn,com…)
   3. authoritative nameserver(权威域名服务器,存储实际 ip): 域名解析商，腾讯，阿里

DNS message format;

command

dig

1. answer section: the actual IP
2. AUTHORITY SECTION: the authoritative name server

DNS recorder

A: hostname and its corresponding ip4 address cname: alias a hostname to another hostname