Default random 10 character string value for SQL Server column

I have a column rndm in my table [guests]. Now, for the column Default value or Binding, whenever a new row is inserted I want to automatically insert a 10-character random string into this column as the default value.

This random string may not contain special characters, only characters from a-zA-Z0-9. What is the best approach to achieve this?

To be clear: I don't want to generate this random string in my .NET code, I want it to be generated within SQL Server.