Dokku and Subdomain forwarding

Hello. I’m a bit new to all this so please bare with me. I’ve set up Dokku with a very simple rails app following: https://www.digitalocean.com/community/tutorials/how-to-use-the-dokku-one-click-digitalocean-image-to-run-a-ruby-on-rails-app

The app is toy-app and I’ve set Dokku to use subdomain like this tutorial: https://www.digitalocean.com/community/tutorials/how-to-use-the-digitalocean-dokku-application

My zone file is:

$TTL	1800
@		IN	SOA	NS1.DIGITALOCEAN.COM.	hostmaster.minhn.net. (
			1409595135 ; last update: 2014-09-01 18:12:15 UTC
			3600 ; refresh
			900 ; retry
			1209600 ; expire
			1800 ; ttl
			)
             IN      NS      NS1.DIGITALOCEAN.COM.
                     NS      NS2.DIGITALOCEAN.COM.
                     NS      NS3.DIGITALOCEAN.COM.
@	IN A	107.170.189.247
*.minhn.net	IN A	107.170.189.247
toy-app	IN A	107.170.189.247
sample-app	IN A	107.170.189.247
*.toy-app	CNAME	toy-app.minhn.net.
*.sample-app	CNAME	sample-app.minhn.net.

I plan on having another app called sample-app and have sample-app.minhn.net go to that app. I want my minhn.net to lead to no where for now. But right now minhn.net and sample-app.minhn.net both goes to toy-app.minhn.net.

Why is this? Is it because the * A record I have? I thought that just meant anything before minhn.net would be forward to the ip but then dokku would check if it matches the subdomain name, if not it won’t serve the app?

Thanks for your time.