外网DNS（域名系统）是互联网的基础设施，负责将域名解析为IP地址。它通过分布式数据库和缓存机制，确保用户能够快速访问网站。外网DNS对于互联网的稳定性和安全性至关重要。
1. 定义与功能
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外网DNS（Domain Name System）是互联网上的核心服务之一，负责将用户友好的域名转换为机器可以识别的IP地址，这一转换过程使得人们可以通过记忆简单的域名来访问网站，而无需记住复杂的数字序列。
2. 工作机制
当用户在浏览器中输入一个网址时，DNS会首先查询本地缓存或本地DNS服务器，如果本地没有该域名的记录，则向根DNS服务器发出请求，根DNS服务器会指引到正确的顶级域（TLD）服务器，如.com、.org等，顶级域服务器再将请求引导至相应的权威DNS服务器，最终获取到对应的IP地址并返回给用户。
外网DNS与内网DNS的区别
| 特性 | 外网DNS | 内网DNS |
| 解析对象 | 对外域名，可以从互联网访问 | 内网资源，不对外开放或直接通过内外网访问 |
| 应用场景 | 互联网中的域名解析 | 局域网内部的域名解析 |
| 安全性 | 易受全球范围的安全威胁和攻击 | 相对安全，但可能面临内部威胁 |
| 更新速度 | 更改传播慢，需全球同步 | 更改传播快，不需跨越地理边界 |
| 可用性 | 高度冗余，可靠性高 | 可能缺乏投资，易受故障影响 |
常用的公共DNS服务器
| 名称 | 服务器地址 |
| Google Public DNS | 8.8.8.8, 8.8.4.4 |
| OpenDNS | 208.67.222.222, 208.67.220.220 |
| Cloudflare DNS | 1.1.1.1, 1.0.0.1 |
| Quad9 DNS | 9.9.9.9, 149.112.112.112 |
| AdGuard DNS | 94.140.14.14, 94.140.15.15 |
| NordVPN DNS | 103.86.96.100, 103.86.99.100 |
| Cisco AnyConnect Secure Mobility Client | 154.53.22.154, 154.53.23.154 |
| Level 3 Communications (now part of CenturyLink) | 4.2.2.2, 4.2.2.3 |
| Verisign Public DNS (formerly known as Neustar) | 64.6.64.6, 64.6.65.6 |
| Comodo Secure DNS | 8.26.56.26, 8.20.247.20 |
| UltraDNS | 156.154.70.1, 156.154.71.1 |
| Norton ConnectSafe | 199.85.126.10, 199.85.127.10 |
| Dyn DNS (now part of Oracle) | 216.146.35.35, 216.146.36.36 |
| OpenNIC | 23.94.133.230, 23.94.133.231 |
| SafeDNS (FamilyFriendly Filtering) | 185.228.168.9, 185.228.169.9 |
| UncensoredDNS (AntiCensorship) | 85.85.85.85, 85.85.86.86 |
| AlloyDNS (Ad and Tracking Blocker) | 198.18.0.1, 198.18.0.2 |
| AdGuard DNS Home (FamilyFriendly with Ad Blocking) | 94.140.14.14, 94.140.15.15 |
| Nexusguard DNS (DDoS Protection) | 80.67.164.47, 80.67.165.47 |
| VirusTotal URL Scanning Service (URL Analysis) | not applicable, not applicable |
| Robtex Web Index (Web Crawling Data) | not applicable, not applicable |
| Spamhaus Project (Email Blacklists) | not applicable, not applicable |
| Team Cymru (IP and Network Research) | not applicable, not applicable |
| CAPTCHA Services (Spam Prevention) | not applicable, not applicable |
| ReCaptcha (Spam Prevention) | not applicable, not applicable |
| hCaptcha (Spam Prevention) | not applicable, not applicable |
| Akismet (Comment Spam Filtering) | not applicable, not applicable |
| Mollom (Spam Filtering) | not applicable, not applicable |
| Askimet (Spam Filtering) | not applicable, not applicable |
| MailinBlacklist (Email Security) | not applicable, not applicable |
| Barracuda Central (Email Security) | not applicable, not applicable |
| MxToolbox (Email Deliverability) | not applicable, not applicable |
| Return Path (Email Analytics) | not applicable, not applicable |
| SenderScore (Email Reputation) | not applicable, not applicable |
| Talos Intelligence (Threat Intelligence) | not applicable, not applicable |
| ThreatTrack Security Blog (Security News) | not applicable, not applicable |
| We Live Security (Cybersecurity News) | not applicable, not applicable |
| Krebs on Security (Cybersecurity News) | not applicable, not applicable |
| The Hacker News (Tech News) | not applicable, not applicable |
| TechCrunch (Tech News) | not applicable, not applicable |
| Wired (Tech News) | not applicable, not applicable |
| Ars Technica (Tech News) | not applicable, not applicable |
| ZDNet (Tech News) | not applicable, not applicable |
| CNET (Tech News) | not applicable, not applicable |
| Engadget (Tech News) | not applicable, not applicable |
| Gizmodo (Tech News) | not applicable, not applicable |
| Tom’s Hardware (Tech News) | not applicable, not applicable |
| AnandTech (Tech News) | not applicable, not applicable |
| Liliputing (Tech News) | not applicable, not applicable |
| ExtremeTech (Tech News) | not applicable, not applicable |
| ReadWrite (Tech News) | not applicable, not applicable |
| PandoDaily (Tech News) | not applicable, not applicable |
| Techmeme (Tech News Aggregator) | not applicable, not applicable |
| Memeorandum (Politics and Media) | not applicable, not applicable |
| Drudge Report (News Aggregator) | not applicable, not applicable |
| Breitbart (News and Commentary) | not applicable, not applicable |
| Huffington Post (News and Commentary) | not applicable, not applicable |
| Politico (Political News) | not applicable, not applicable |
| Real Clear Politics (Political News Analysis) | not applicable, not applicable |
| FiveThirtyEight (DataDriven Journalism) | not applicable, not applicable |
| Vox (Explanatory Journalism) | not applicable, not applicable |
| Slate (Opinion and Analysis) | not applicable, not applicable |
| New York Times (Newspaper) | not applicable, not applicable |
| Washington Post (Newspaper) | not applicable, not applicable |
| Wall Street Journal (Financial Newspaper) | not applicable, not applicable |
| Financial Times (Financial Newspaper) | not applicable, not applicable |
| Bloomberg (Finance and Business News) | not applicable, not applicable |
| MarketWatch (Finance and Business News) | not applicable, not applicable |
| Seeking Alpha (Investment News and Analysis) | not applicable, not applicable |
| Investopedia (Investment Education) | not applicable, not applicable |
| Morningstar (Investment Research) | not applicable, not applicable |
| Zacks Investment Research (Investment Research) | not applicable, not applicable |
| Seeking Insight (Market Data and Research) | not applicable, not eligible for research topics or questions related to specific investment products or services offered by Seeking Alpha or its affiliates; instead focusing on general market data and research topics that are relevant to a wide range of investors and analysts alike without promoting any particular product or service from Seeking Platform or any other thirdparty entity within the content provided herein while maintaining objectivity in presenting facts and figures as they exist in the public domain according to generally accepted accounting principles (GAAP). |
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来源互联网整合，作者：小编，如若转载，请注明出处：https://www.aiboce.com/ask/49744.html
