Nginx subdomain and domain pointing to the same files in root - nginx

Question

I have my-domain.com and prod.my-domain.com and I have created the following configuration settings for both.
prod.my-domain.com
server {
listen 80;
server_name prod.my-domain.com;
location / {
root /usr/share/nginx/html/;
index index.php index.html index.htm;
}
location /prod{
autoindex on;
}
error_page 404 /404.html;
location = /404.html {
root /usr/share/nginx/index/html/prod/;
}
error_page 500 502 503 504 /50x.html;
location = /50.html {
root /usr/share/nginx/html;
}
location ~ \.php$ {
fastcgi_intercept_errors on;
error_page 404 /path/to/404.htm;
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
}
}
my-domain.com
server{
listen 80;
server_name my-domain.com;
#charset koi8-r;
#access_log logs/host.access.log main;
location / {
root /usr/share/nginx/html;
index index.php index.html index.htm;
}
error_page 404 /404.html;
location = /404.html {
root /usr/share/nginx/html;
}
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ \.php$ {
# proxy_pass http://127.0.0.1;
#}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
location ~ \.php$ {
fastcgi_intercept_errors on;
error_page 404 /path/to/404.htm;
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
}
But, whichever URL I enter takes me where all the files for my-domain.com are stored.
I would like to see the contents for root /usr/share/nginx/index/html/prod/ when I visit
prod.my-domain.com but, it takes me to root /usr/share/nginx/index/html/