There are a couple ways to account for this type of user error:
The Specific Method
If you want to be specific, you can create A Record‘s with your DNS provider that logically direct to the intended sub domain (so in my example above, I would create a new A Record that points “erik.forsbergville.com to eric.forsbergville.com.
The Catchall (Wildcard) Method
To create an all powerful sub-domain catchall, you simply need to create a wildcard DNS record. So with my domain host, GoDaddy, I use the Zone Editor to create a new A Record with “*” for the name field and my server IP address for the IP field.