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DNS over HTTPS (DoH)

  • Cloudflare: DNS over HTTPS

  • Google Public DNS: DoH JSON API

  • Wikipedia: DNS over HTTPS

  • JSON

    • 只支持 GET，查询编码在 URL；Cloudflare 需要 Accept: application/dns-json
    • 没有 RFC，Cloudflare 沿用 Google 的 schema，各家行为可能不同；严格场景用 wire format
    • 参数：name（必填）、type（默认 A）、do（DNSSEC）、cd（关闭校验）

  • wire format - RFC 8484，application/dns-message

    • GET：?dns=<base64url DNS 报文>
    • POST：body 为二进制报文，必须设置 Content-Type: application/dns-message，否则返回 415

Status Codes​

  • 400 DNS query not specified or too small.
  • 413 DNS query is larger than maximum allowed DNS message size.
  • 415 Unsupported content type.
  • 504 Resolver timeout while waiting for the query response.

Examples​

# Cloudflare JSON
curl -H 'accept: application/dns-json' 'https://cloudflare-dns.com/dns-query?name=example.com&type=AAAA'
curl -H 'accept: application/dns-json' 'https://1.1.1.1/dns-query?name=example.com&type=A&do=1'

# Google JSON
curl 'https://dns.google/resolve?name=example.com&type=AAAA'
# ct=application/x-javascript 显式请求 JSON；ct=application/dns-message 则返回二进制 DNS 报文
curl 'https://dns.google/resolve?name=example.com&type=A&ct=application/x-javascript'
{
  "Status": 0,
  "TC": false,
  "RD": true,
  "RA": true,
  "AD": true,
  "CD": false,
  "Question": [{ "name": "example.com.", "type": 28 }],
  "Answer": [{ "name": "example.com.", "type": 28, "TTL": 1726, "data": "2606:2800:220:1:248:1893:25c8:1946" }]
}
  • Status 是 DNS RCODE：0 NOERROR，2 SERVFAIL，3 NXDOMAIN
  • type 为数字：1 A，5 CNAME，28 AAAA