DNS协议

DeeLMind大约 1 分钟

DNS协议

什么是DNS协议?

域名系统(英语:Domain Name System,缩写:DNS)是互联网的一项服务。它作为将域名和IP地址相互映射的一个分布式数据库,能够使人更方便地访问互联网。DNS使用TCP和UDP端口53。当前,对于每一级域名长度的限制是63个字符,域名总长度则不能超过253个字符。

DNS系统组成

  • root 根域名
  • 顶级域名
  • 二级域名
  • 三级域名
  • 四级域名
deelmind.com.
. root域名
com 顶级域名
deelmind 二级域名

DNS解析流程

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  • 本地HOSTS文件解析
C:\Windows\System32\drivers\etc\hosts

# Copyright (c) 1993-2009 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
#      102.54.94.97     rhino.acme.com          # source server
#       38.25.63.10     x.acme.com              # x client host

# localhost name resolution is handled within DNS itself.
#	127.0.0.1       localhost

DNS Records Typesopen in new window

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  • A 记录(IPv4 Address Record)
  • MX 记录(Mail Exchanger Record)
  • NS 记录(Name Server Record)
  • PTR 记录(Pointer Record)
  • SOA 记录(Start of Authority Record)
  • SRV 记录(Service Record)
  • TXT 记录(Text Record)
  • AAAA 记录(IPv6 Address Record)
  • CNAME 记录(Canonical Name Record)

DNS Root Serveropen in new window

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贡献者: DeeLMind