内容简介

本文将介绍与BIND有关的基础内容，以及与DNS服务相关的基础内容。通过BIND加深对DNS的理解。

常见术语

# DNS Forwarding

转发，如字面意思，在「客户端直连的服务器」收到解析请求时，它将查询请求直接转发到另外一台主机，而本身不进行解析。

术语「DNS forwarding」只指：将特定DNS请求转发到指定的DNS服务器以进行解析的过程。

# 转发和递归的区别

「What’s the difference between recursion and forwarding in bind」
「dns分类与区别-权威DNS、递归DNS、转发DNS」

Forwarding

just passes the DNS query to another DNS server (e.g. your ISP’s). Home routers use forwarding to pass DNS queries from your home network’s clients to your ISP’s DNS servers.

For example, for foo.example.com, a forwarding DNS server would first check its cache (did it already ask this question before), and if the answer is not in its cache, it would ask its forwarder (your ISP’s DNS server) for the answer, which would respond with either a cached response, or would perform recursion until it figured out the answer.

Recursion

the DNS server receiving the query takes it upon itself to figure out the answer to that query by recursively querying authoritative DNS servers for that domain.

For example, for foo.example.com, a recursor would first query the root servers for what DNS servers are responsible for the .com TLD, then it would ask those servers for example.com, then it would query the servers for example.com for foo.example.com, finally getting the answer to the original query.

服务类型

DNS服务器由众多类型

Authoritative-Only DNS Servers
Caching DNS Server
Forwarding DNS Server
Combination Solutions

参考文献

A Comparison of DNS Server Types: How To Choose the Right DNS Configuration