一、现象
全站不能访问
二、网络层排查
# 从外部网络测试连接curl-vhttps://www.example.com# * Could not resolve host: www.example.com# 换一个DNS服务器试试nslookupwww.example.com8.8.8.8# Server: 8.8.8.8# Address: 8.8.8.8#53## ** server can't find www.example.com: SERVFAIL# 再试试其他DNSnslookupwww.example.com1.1.1.1# Server: 1.1.1.1# Address: 1.1.1.1#53## ** server can't find www.example.com: SERVFAIL三、DNS深入诊断
# 使用dig进行详细诊断digwww.example.com +trace# 输出（简化）：# . 518400 IN NS a.root-servers.net.# com. 172800 IN NS a.gtld-servers.net.# example.com. 172800 IN NS ns1.dnsprovider.com.# ;; <<>> DiG 9.11.4 <<>> www.example.com +trace# ;; Query time: 45 msec# ;; connection timed out; no servers could be reached# 权威DNS服务器无法响应# 检查域名的NS记录digexample.com NS# 尝试直接查询权威DNSdig@ns1.dnsprovider.com www.example.com# ;; connection timed out; no servers could be reached四、域名状态查看
# 使用whois查询域名状态whois example.com# Domain Name: EXAMPLE.COM# Registry Domain ID: 123456789# Registrar: Example Registrar Inc.# Domain Status: serverHold https://icann.org/epp#serverHold# Updated Date: 2022-08-15T03:00:00Z# Creation Date: 2017-08-15T00:00:00Z# Registry Expiry Date: 2022-08-15T00:00:00Z五、总结
# DNS故障排查清单## 1. 确认DNS是否正常digwww.example.com +shortnslookupwww.example.com8.8.8.8## 2. 检查域名状态whois example.com|grep-E"Status|Expiry"## 3. 追踪DNS解析路径digwww.example.com +trace## 4. 检查权威DNSdigexample.com NSdig@ns1.provider.com www.example.com## 5. 检查DNS记录digwww.example.com Adigwww.example.com CNAMEdigexample.com MXdigexample.com TXT## 6. 检查DNS提供商状态# 访问DNS提供商状态页面## 7. 检查网络连通性pingns1.provider.comtraceroutens1.provider.com## 8. 常见状态码解释# NOERROR: 正常# NXDOMAIN: 域名不存在# SERVFAIL: 服务器错误# REFUSED: 拒绝服务## 9. 域名状态解释# ok/active: 正常# serverHold: 被注册局暂停（通常是欠费或违规）# clientHold: 被注册商暂停# pendingDelete: 等待删除# redemptionPeriod: 赎回期
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