When you select this option, users must have an Internet connection each time they access the document. If you later revoke ...

When you select this option, users must have an Internet connection each time they access the document. If you later revoke access to the document by using the document tracking site,  revocation is immediate and users can no longer access the document.
If you do not select this option, revocation can take some time to take effect. However, users might not need an Internet connection each time they access the document.