As you asking I am telling following Identification Documents will have needed when you will go to appear in CAT Exam:


CAT Admit Card

At least one valid and original photo ID. The name on the photo ID must be
similar to the name in the CAT Application form. Acceptable photo IDs are:

Driving License

Passport

PAN Card

Voter ID card

Employee ID card

Unique Identification Card (UID)

College ID (supported with a valid ATM . Credit / Debit card with candidates’
name)

A notarized affidavit (in English) with photo, Signature, Date of Birth and
Residential Address.

CAT exam pattern can be explained as below sections & topics:

The Quantitative Ability section will comprise of questions on topics like:

Mathematics
Arithmetic
Geometry
Mensuration

While Data Interpretation & Logical Reasoning section includes questions on:

Graphs
Charts
Ability to comprehend

Verbal Ability & Reading Comprehensions questions judge:

English Language Skills