Defensive Design

Question 1

What is the purpose of defensive design?

Answer 1

Ensure a program is secure and robust

Question 2

Name the 6 defensive design considerations

Answer 2

Anticipating misuse, input sanitisation, validation, verification, authentication, maintainable code

Question 3

What is validation?

Answer 3

Process to check that data is reasonable or sensible before it is accepted

Question 4

What is a range check?

Answer 4

Checks data is within a certain range

Question 5

What is a type check?

Answer 5

Checks data is a certain type

Question 6

What is a format check?

Answer 6

Checks data is entered in a certain way

Question 7

What is a presence check?

Answer 7

Checks that data has actually been entered and not left blank

Question 8

What is a lookup table?

Answer 8

A table of acceptable entries, also known as a list

Question 9

What is a length check?

Answer 9

Checks the length of the input is within a certain amount

Question 10

What is maintainability and why should it be used?

Answer 10

Programs should be written in a way that makes maintaining and understanding them as straightforward as possible

Question 11

List the 5 ways of keeping maintainability in a program

Answer 11

Subprograms (modularisation), appropriate variable names, indentation, comments, constants

Question 12

Modularisation

Answer 12

Using subprograms to reuse code and make them easier to test

Question 13

Indentation

Answer 13

Improves readability and clearly shows each ‘block’ of code

Question 14

Comments

Answer 14

Enable a programmer to understand the purpose of each line of code; it is crucial when working in a team

Question 15

Appropriate variable names

Answer 15

Using a naming convention ensures the purpose of a variable is immediately understood

Question 16

Constants

Answer 16

Keeps the program code consistent, which makes it easier to read and debug a program