Tradeoffs in Implementing Defense in Depth Paper

Describe how design principles of abstraction, modularity, and layering help with security.
Describe tradeoffs in implementing defense in depth to protect computers and software applications in a company.
A domain name server (DNS) converts human-readable addresses like “google.com” to computer-readable IP addresses like “173.194.67.102”. Your computer has a local DNS cache, so it can quickly refer to DNS lookups it’s already performed rather than performing a DNS lookup over and over again. Discuss the tradeoffs in this design.
In a small company when an employee enters a building he/she has access to all rooms. Which four principles of security are violated in this practice?
An application is divided into components as shown in the picture. Which design principle(s) is (are) applied in this scenario? Explain.