Na I doubt an interview question, prolly homework would be my best bet.
When you do explain could you also explain what is 3 tier architecture and its relation to frameworks in php? Thanks
3 tier = grand parent, parent, child?
Back to school for me it seems :D HA
He's probably mistaken the term '3 tier' to mean MVC or Model, View and Controller. A lot of PHP frameworks (most) are based off of this design philosophy. In an MVC Framework the Model (the database in this case) acts separately of the View (any html output), and the Controller (any business logic) which controls it all. The main reason for this is so you don't have a bunch of database queries and PHP code in your template files.
According to wikipedia (I know, not the best place for info) 3-tier consists of the presentation tier, application logic (business logic, ect) tier, and data tier. This is pretty much the workings of a webserver.
Presentation tier is anything outputted to the browser, application logic is the php code itself, and data tier is the database (MySQL,ect.).
I think it can exist without a framework. Linear coding can practice this from my understanding, but I could be wrong.
Also, 3-tier is different from MVC in the fact that 3-tier works in a linear way rather than MVCs' triangle approach.