This is what I see using dig:
Please try removing your domain from your InfinityFree account and add it back again.
If you don’t know how, you can follow this post:
Note that when you removed and added the domain, it created a new folder for you. Instead of using the /htdocs folder, you now have to use the /vimal.ramdhunee.com/htdocs folder.
Using FTP, move the files from the original htdocs folder to the new one that was created for you.
I noticed that the domain does not lead anywhere nor is it hosted by us
We don’t formally support hosting subdomains (vimal.ramdhunee.com) without their own custom domains (ramdhunee.com) on our hosting. So it may break at some point.
unofficially it is possible but…
It would be ideal if you:
could try to add the domain name to your account here as usual, and set up the subdomain through the Subdomains menu.
After that, you can move the main domain (ramdhunee.com) back to wherever it was hosted before.
Just make sure not to delete the domain from your account, or you won’t be able to create more subdomains.