Certification coverage

Answer:

The certification coverage will depend on the ISMS scope definition. If it is issued to corporate X, then we need to verify which locations (i.e., addresses) where included. If the address of any subsidiary or affiliated entity is included, then it is covered by the certificate (of course this entity will have to go through all certification process together with the main Corporate X)

Adopting a single certificate for all units or separated ones for each unit is a business decision, depending on their objectives and strategies, but in general organizations like these adopt the model of one certification for each unit, because a change on an unit does not impact the certification of other units.

These articles will provide you further explanation about scope definition:
- How to define the ISMS scope https://advisera.com/27001academy/knowledgebase/how-to-define-the-isms-scope/
- Problems with defining the scope in ISO 27001 https://advisera.com/27001academy/blog/2010/06/29/problems-with-defining-the-scope-in-iso-27001/