First off is a methodology which matches the written policies and procedures of the entity seeking the assessment. I frequently see the methodology dictated by the provider, not by the client. As a client you should be asking (possibly different providers) at minimum for:
- Internal and external network vulnerability testing
- Internal and external penetration testing for both application and network layers
- Segmentation testing
- API penetration testing
- Web application vulnerability testing.
Each of these types of tests then needs to be applied to all appropriate in-scope elements of the cardholder data environment (CDE). Generally, you will provide either a list of URLs or a list of IP addresses to the tester. PCI requires that all publicly reachable assets associated with payment pages be submitted for testing. In as much as dynamic IP assignment is very common, especially in Cloud environments, ensure that you are providing a consistent set of addressing information across quarterly testing orders.