A content delivery network (CDN) is a network of servers that deliver web content to users based on their geographic location. A CDN can improve the performance, reliability, and security of a web application by caching content closer to the users and reducing the load on the origin server.
One of the security advantages of using a CDN is that it can provide resiliency against distributed denial-of- service (DDoS) attacks, which are attempts to overwhelm a web server with a large number of requests from multiple sources. A CDN can mitigate DDoS attacks by:
Distributing the traffic across multiple servers and locations, making it harder for attackers to target a single point of failure Filtering out malicious requests before they reach the origin server, using techniques such as rate limiting, IP blocking, and challenge-response mechanisms Absorbing the attack traffic with greater bandwidth and resources than the origin server, reducing the impact on the web application's availability and performance

Shadow IT is the use of IT-related hardware or software by a department or individual without the knowledge of the IT or security group within the organization. It can encompass cloud services, software, and hardware.