DNS
DOMAIN NAME SYSTEM · REFERENCE GUIDE
DNS FUNDAMENTALSShare:
DNS translates human-readable domain names into records that help browsers, mail servers and other services locate the right destination. This guide explains the most useful record types and how to inspect them safely.
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01. DNS 如何工作？
When a client looks up a domain, a resolver checks cached answers and may query authoritative name servers. The response contains DNS records and a time-to-live (TTL) value that helps determine caching behavior.
1输入域名
example.com
→example.com
2Query a resolver
DNS lookup
→DNS lookup
3Read the records
Answer + TTL
Answer + TTL
02. 常见 DNS 记录类型
Each record type serves a different purpose. The table below summarizes common examples; actual values vary by domain and configuration.
| 类型 | Purpose | Example value |
|---|---|---|
| A | Maps a name to IPv4 | 192.0.2.10 |
| AAAA | Maps a name to IPv6 | 2001:db8::10 |
| MX | Routes incoming email | 10 mail.example.com |
| NS | Identifies authoritative servers | ns1.example.net |
| TXT | Stores text-based policies | v=spf1 -all |
| CAA | Restricts certificate issuers | 0 issue "letsencrypt.org" |
The IP addresses above are documentation-only examples, not live DNS results.