curl -vv -6 
https://www.zhihu.com* About to connect() to 
www.zhihu.com port 443 (#0)
*   Trying 240e:cf:9000:321:37::13...
* Connected to 
www.zhihu.com (240e:cf:9000:321:37::13) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
*   CAfile: /etc/pki/tls/certs/ca-bundle.crt
  CApath: none
* SSL connection using TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
* Server certificate:
*       subject: CN=*.zhihu.com,O=智者四海(北京)技术有限公司,ST=北京市,C=CN
*       start date: Dec 10 00:00:00 2024 GMT
*       expire date: Jan 10 23:59:59 2026 GMT
*       common name: *.zhihu.com
*       issuer: CN=GeoTrust G2 TLS CN RSA4096 SHA256 2022 CA1,O="DigiCert, Inc.",C=US
> GET / HTTP/1.1
> User-Agent: curl/7.29.0
> Host: 
www.zhihu.com> Accept: */*
> 
< HTTP/1.1 525 EO errCode : SSL handshake failed
< Server: EdgeOne_IS_OC
< Content-Length: 0
< Connection: keep-alive
< Date: Fri, 17 Oct 2025 02:08:16 GMT
< alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43"
< EO-LOG-UUID: 5273955530657146703
< 
* Connection #0 to host 
www.zhihu.com left intact