CPK - DTM Test Log File is a file extension used for testing reports from DTM. You can easily use this program extension when it comes to logging information about a hardware device. You will also be able to use this extension for submitting test results to Microsoft. This is very handy so that a device may be certified for Windows. It also comes in handy for debugging tests that may have failed already. You can view different CPK files using the DTM log viewer. There is a lot of important information that is shown to you through the viewer.