CAS documentation has moved over to jasig apereo.github.io/cas, starting with CAS version 4.x. The wiki will no longer be maintained. For the most recent version of the documentation, please refer to the aforementioned link.
Versions prior to CAS 3.3.5, had a simplistic approach to throttling attempts based on IP Addresses. Since CAS 3.3.5, those options have been expanded.
For single node CAS instances, there are two in-memory approaches: One by IP Address, and one by IP Address + username combination.
For multi-node CAS instances there is one option that combines the auditing capabilities of the Inspektr package with the throttling package (and relies on a database).