Okay I have resolved the issue. So I will answer this for future reference of other people.

You need to check 2 important places.

1. /etc/nginx/sites-enabled/<your_project>

If you want your django app with just the subdomain, your project file in sites-enabled should look like below.

server {
    listen 80;
    server_name <ip-address> .X.com;

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        root /home/eleena/reporting_app;
    }

    location / {
        include proxy_params;
        proxy_pass http://unix:/home/eleena/reporting_app.sock;
    }

The dot in front of X.com is not a typo. This basically says any sub domain for X.com.

1. settings.py file in Django App

You have to set ALLOWED_HOSTS this way.
ALLOWED_HOSTS = ['ip-address', '.X.com']
Again X.com is preceded with a dot.

In the question, I already mentioned that I created an A record with following details.

Host- reporting
Type - A
Content - <ip-address> of digital ocean droplet

After this, restart your nginx server.
sudo systemctl restart nginx

Now, theoretically it should work. But if it doesn’t (as it didn’t for me), you have to shutdown and restart your droplet.

sudo shutdown -r now

My Django app started to work after this activity.
Hope it helps.

The good news is your A record is pointing to your Droplet and is resolving correctly.

I assume you have created a Nginx conf for your subdomain and set the server_name property to reporting.x.com?

Restart Nginx after setting your conf by running:

systemctl restart nginx