What security methodology involves placing multiple layers of defense throughout a network infrastructure?

The concept of "Defense in depth" is centered around the idea of protecting an organization's network and information systems by implementing multiple layers of security controls. This approach is designed to provide redundancy in the event that one layer of security fails, ensuring that if an attacker penetrates one layer, there are additional layers that can prevent further access or mitigate damage.

Defense in depth encompasses various security measures, such as firewalls, intrusion detection systems, encryption, access controls, and physical security measures, all working together to secure the overall infrastructure. This strategy not only enhances security but also provides multiple opportunities to detect and respond to potential threats.

Other methodologies mentioned do focus on security, but they do not specifically advocate for the layered approach that is central to defense in depth. For instance, threat modeling is a technique used to identify potential vulnerabilities by analyzing the architecture and other aspects of an application or system, rather than establishing multiple security layers. Identity as the security perimeter emphasizes securing user identities and access management, shifting traditional boundaries, while the shared responsibility model outlines the division of security responsibilities between cloud providers and their customers, but it doesn't embody the layered approach itself.