I am looking at getting an ipad pro but before I do I am wondering if it can support a CAC reader?

Depends on the reader.

The iPad has no native support for them, nut some readers have Apps that allow the iPad to work with them.

For example:

http://www.thursby.com/products/pkard-reader-apple

CAC is short for Common Access Card.

Used in highly secure organizations and corporate environments such as military installations to access restricted areas and resources .

Many corporate computers use CACs to log into them.

Don’t know what this is.

What is a CAC reader?