To maintain security, which routing type may Cloud Routers not use for all resources?

Global routing is the correct choice because it is designed to manage network traffic across multiple regions and is not limited to specific zones or regions, which can raise security concerns. Since global routing encompasses a wider area, it may expose resources to potential vulnerabilities that can arise from cross-region communications, making it necessary to evaluate its use carefully in sensitive environments.

On the other hand, regional routing specifically focuses on managing traffic within a particular region, allowing for tighter control over the network and its resources. This limits the exposure of sensitive data and systems to other regions. Static routing offers a more manual and controlled approach to network paths, which can enhance security by allowing administrators to define specific routes without the dynamic elements that might introduce risks. Default routing acts as a catch-all solution but within a defined path, making it easier to manage traffic but still offers a good level of security as it can lead traffic to fewer points of exposure.

Therefore, while each routing type has its benefits and potential security implications, global routing presents the greatest challenge in terms of maintaining security for all resources within a cloud environment.