*.example.com -> 1.2.3.4
*.anotherexample.com -> 1.2.3.4

server {

  listen 80;

  server_name
    example.com
    www.example.com
    *.example.com;

  location /.well-known {
    alias /var/www/html/letsencrypt;
  }

  location / {

    proxy_pass_header Authorization;
    proxy_pass http://address.of-the.internal.example-webserver
    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_http_version 1.1;
    proxy_set_header Connection "";
    proxy_buffering off;
    client_max_body_size 0;
    proxy_read_timeout 36000s;
    proxy_redirect off;
    access_log /var/log/nginx/example.com.log;
    error_log /var/log/nginx/example.com.log error;

  }
}

server {

  listen 80;

  server_name
    anotherexample.com
    www.anotherexample.com
    *.anotherexample.com;

  location /.well-known {
    alias /var/www/html/letsencrypt;
  }

  location / {

    proxy_pass_header Authorization;
    proxy_pass http://address.of-the.internal.anotherexample-webserver
    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_http_version 1.1;
    proxy_set_header Connection "";
    proxy_buffering off;
    client_max_body_size 0;
    proxy_read_timeout 36000s;
    proxy_redirect off;
    access_log /var/log/nginx/anotherexample.com.log;
    error_log /var/log/nginx/anotherexample.com.log error;

  }
}

server {

  listen 80;

  server_name application1.example.com;

  location / {

    proxy_pass_header Authorization;
    proxy_pass http://internal.address.of-example-app-one
    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_http_version 1.1;
    proxy_set_header Connection "";
    proxy_buffering off;
    client_max_body_size 0;
    proxy_read_timeout 36000s;
    proxy_redirect off;
    access_log /var/log/nginx/exampleappone.access.log;
    error_log /var/log/nginx/exampleappone.error.log error;

  }
}

server {

  listen 80;

  server_name application2.example.com;

  location / {

    proxy_pass_header Authorization;
    proxy_pass http://internal.address.of-example-app-two
    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_http_version 1.1;
    proxy_set_header Connection "";
    proxy_buffering off;
    client_max_body_size 0;
    proxy_read_timeout 36000s;
    proxy_redirect off;
    access_log /var/log/nginx/exampleapptwo.access.log;
    error_log /var/log/nginx/exampleapptwo.error.log error;

  }
}

server {

  listen 80;

  server_name application1.anotherexample.com;

  location / {

    proxy_pass_header Authorization;
    proxy_pass http://internal.address.of-anotherexample-app-one
    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_http_version 1.1;
    proxy_set_header Connection "";
    proxy_buffering off;
    client_max_body_size 0;
    proxy_read_timeout 36000s;
    proxy_redirect off;
    access_log /var/log/nginx/anotherexampleappone.access.log;
    error_log /var/log/nginx/anotherexampleappone.error.log error;

  }
}