求助， nginx 多站点配置，无法通过域名访问，使用 ip 访问会跳转到其中一个站点

在一台服务器设置了 Nginx 多站点，但是访问这些站点的域名均无法访问，错误如下图：

通过 ip 会跳转到其中一个站点，具体表现为：

全部配置开启的情况下所有域名无法访问， ip 访问显示的是siteD 去除 siteD 后跳转 siteB,去除 siteB 后 404 ，去除 siteB 后跳转 siteA ，去除 siteA 后跳转 siteC

检查了半天还是不知道是啥问题，请各位大神帮忙排查下 /w\

以下为具体配置文件：

nginx.conf

user  nginx;
worker_processes  1;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    server_tokens   off;
    underscores_in_headers off;

    keepalive_timeout  65;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;
}

default.conf

server {
    listen       80;
    server_name  _;

    location / {
        return 404;
    }
}

siteA.conf

server {
    listen       80;
    server_name  siteA.domain.com;

    access_log  /var/log/nginx/siteA.access.log  main;

    location / {
        root   /usr/share/nginx/html/siteA;
        index  index.php index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    location ~ \.php$ {
         #try_files $uri =404;
         #root /usr/share/nginx/html/siteA;
         fastcgi_split_path_info ^(.+.php)(/.+)$;
         fastcgi_pass unix:/dev/shm/php5.6-fpm.sock;
         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
         fastcgi_index index.php;
         include fastcgi_params;
    }
}

siteB.conf

server {
    listen       80;
    server_name  siteB.domain.com;

    access_log  /var/log/nginx/siteB.access.log  main;

    location / {
        root   /usr/share/nginx/html/siteB;
        index  index.php index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    location ~ \.php$ {
         try_files $uri =404;
         root /usr/share/nginx/html/siteB;
         fastcgi_split_path_info ^(.+.php)(/.+)$;
         fastcgi_pass unix:/dev/shm/php5.6-fpm.sock;
         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
         fastcgi_index index.php;
         include fastcgi_params;
    }
}

siteC.conf

server {
    listen       80;
    server_name  siteC.domain.com;

    access_log  /var/log/nginx/siteC.access.log  main;

    location / {
        root   /usr/share/nginx/html/siteC/;
        index  index.php index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }

    location ~ \.php$ {
         try_files $uri =404;
         root /usr/share/nginx/html/siteC/;
         fastcgi_split_path_info ^(.+.php)(/.+)$;
         fastcgi_pass unix:/dev/shm/php5.6-fpm.sock;
         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
         fastcgi_index index.php;
         include fastcgi_params;
    }
}

siteD.conf

server {
    listen       80;
    server_name  siteD.domain.com;

    access_log  /var/log/nginx/siteD.access.log  main;

    location ~ ^/(baidu|webscan|yx_scan) {
        root /usr/share/nginx/siteD;
    }

    location / {
	   proxy_set_header Host $host;
	   proxy_set_header X-Real-IP $remote_addr;
	   proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
	   proxy_set_header User-Agent $http_user_agent;
	   proxy_set_header Accept-Encoding "";
	   proxy_redirect off;
	   proxy_pass http://127.0.0.1:8080/siteD/;
	   rewrite ^/WebGoat/(.*)$ /$1 last;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

Nginx Info (使用 apt 安装， mainline)

nginx version: nginx/1.11.9
built by gcc 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04.3) 
built with OpenSSL 1.0.1f 6 Jan 2014
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fPIC' --with-ld-opt='-Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -pie'