As you have asked about the time duration and exam pattern for the National Aptitude test for Architecture (NATA), I am giving you information about it

The test is in two parts.
A paper based drawing test and
Computer based online aesthetic sensitivity test.

The test measures aptitude of the candidate through two sections – a paper based section for drawing and computer based section for aesthetic sensitivity.
This is a two hour paper where candidate has to attempt three questions.

Drawing Test

This is a two hour paper where candidate has to attempt three questions. The drawing aptitude is judged on the following aspects –

Ability to sketch a given object proportionately and rendering the same in visually appealing manner
Visualising and drawing the effects of light on the object and shadows cast on surroundings.
Sense of perspective drawing
Combining and composing given three dimensional elements to form a building or structural form.
Creating interesting two dimensional composition using given shapes and forms.
Creating visual harmony using colours in given composition.
Understanding of scale and proportions through pencil sketch on themes from day to day experiences.

Aesthetic Sensitivity Test

This is computer based test where candidate has to answer 40 multiple choice questions.
The aesthetic sensitivity test measures perception, imagination and observation, creativity and communication along with architectural awareness and comprises of –

Visualising three dimensional objects from two dimensional drawings
Visualising different sides of three dimensional objects
Identifying commonly used materials and objects based on their textural qualities.
Analytical reasoning
Mental Ability
Imaginative comprehension and expression
Architectural awareness