Producing Robust Programs

Question 1

what is the purpose of defensive design

Answer 1

to ensure that a program runs correctly and continues to run no matter what

Question 2

what three areas does defensive design encompass

Answer 2

• protection against unexplained user inputs
• maintainability
• minimising/removing bugs

Question 3

List 5 ways in which defensive design is done

Answer 3

Sanitisation
Validation
authentication
testing 
maintainance

Question 4

Explain 3 examples of validation that can be built into a program

Answer 4

Range Check-the item entered must be in the range given
Length Check- the item must not be too long or too short
Format Check-the data must be in the correct format

Question 5

What does validation not do

Answer 5

ensure that the data is correct-it only checks that it is valid and sensible

Question 6

What is the purpose of data sanitisation

Answer 6

to hide or protect data so it cannot be seen or disclosed

Question 7

What is masking and what does it do?

Answer 7

masking hides data by replacing it with something else. an example of this is passwords

Question 8

What is input sanitisation

Answer 8

checks data that is entered and removes anything that could be potentially dangerous

Question 9

What is authentication, list 3 factors of it

Answer 9

a user confirming that they are who they say they are on a computer system
The 3 factors of this are:
something you are (eg username)
something you know (eg password)
something you have (eg biometrics)

Question 10

What is the purpose of maintainability?

Answer 10

to ensure that over time a product can be easily maintained