Class should always specify default values for every parameter. If they do not, then you have to use the parameterized class syntax and cannot use `include` which is an anti-pattern. This means that in another module that needs to include the class to ensure that dhcp is setup, it also has to use the parameterized class syntax with exactly the same params as used elsewhere in the code base. This violates DRY and is next to impossible for people to implement.