Did a tail -f while trying to access it, the result as below:
[root@ringgum log]# tail -f nginx/error.log
2014/11/05 11:52:56 [error] 17862#0: *1 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 198.35.44.120, server: ringgum.eu, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/opt/configs/php-fpm/sock/admin.sock:", host: "webmail.ringgum.eu"
2014/11/05 11:52:56 [error] 17862#0: *1 testing "/home/admin/ringgum.eu" existence failed (2: No such file or directory) while logging request, client: 198.35.44.120, server: ringgum.eu, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/opt/configs/php-fpm/sock/admin.sock", host: "webmail.ringgum.eu"
2014/11/05 11:53:04 [error] 17862#0: *8 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 198.35.44.120, server: ringgum.eu, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/opt/configs/php-fpm/sock/admin.sock:", host: "
www.ringgum.eu"
2014/11/05 11:53:04 [error] 17862#0: *8 testing "/home/admin/ringgum.eu" existence failed (2: No such file or directory) while logging request, client: 198.35.44.120, server: ringgum.eu, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/opt/configs/php-fpm/sock/admin.sock", host: "
www.ringgum.eu"
2014/11/05 11:53:05 [error] 17862#0: *8 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 198.35.44.120, server: ringgum.eu, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://unix:/opt/configs/php-fpm/sock/admin.sock:", host: "
www.ringgum.eu"
2014/11/05 11:53:05 [error] 17862#0: *8 testing "/home/admin/ringgum.eu" existence failed (2: No such file or directory) while logging request, client: 198.35.44.120, server: ringgum.eu, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://unix:/opt/configs/php-fpm/sock/admin.sock", host: "
www.ringgum.eu"