60.9.4.131 无法访问 504 Gateway Time-out
$ dig v2ex.assets.uxengine.net @114.114.114.114 +sort |\ grep -oE '\b([0-9]{1,3}\.){3}[0-9]{1,3}\b' |\ xargs -I{} curl https://v2ex.assets.uxengine.net --verbose --resolve v2ex.assets.uxengine.net:443:{} * Added v2ex.assets.uxengine.net:443:60.9.4.131 to DNS cache * Rebuilt URL to: https://v2ex.assets.uxengine.net/ * Hostname v2ex.assets.uxengine.net was found in DNS cache * Trying 60.9.4.131... * TCP_NODELAY set * Connected to v2ex.assets.uxengine.net (60.9.4.131) port 443 (#0) * TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 * Server certificate: v2ex.co * Server certificate: Let's Encrypt Authority X3 * Server certificate: DST Root CA X3 > GET / HTTP/1.1 > Host: v2ex.assets.uxengine.net > User-Agent: curl/7.54.0 > Accept: */* > < HTTP/1.1 504 Gateway Time-out < Server: nginx/1.15.8 < Date: Fri, 28 Dec 2018 18:42:56 GMT < Content-Type: text/html < Content-Length: 167 < Connection: keep-alive < X-ORCA-Accelerator: MISS from k01.uni.gan01.cn.krill.zenlogic.net < X-Cache: MISS from k01.uni.gan01.cn.krill.zenlogic.net < <html> <head><title>504 Gateway Time-out</title></head> <body> <center><h1>504 Gateway Time-out</h1></center> <hr><center>nginx/1.15.8</center> </body> </html> * Connection #0 to host v2ex.assets.uxengine.net left intact