DoS attacks are a type of security threat where a computer is flooded with TCP and UDP packets, rendering it unable to respond to legitimate requests. In contrast, DDoS (Distributed Denial of Service) attacks involve multiple systems attacking a single target, making it even more difficult to defend against.

Public networks, such as the internet, are more vulnerable to DoS attacks because they are accessible to anyone with an internet connection. Attackers can easily target public networks with a large number of requests, overloading the servers and causing the network to crash. In contrast, internal/private networks are more secure because they are isolated from the public network and are typically accessible only to authorised users. This makes it more difficult for attackers to launch DoS attacks against these networks, as they need to gain unauthorised access to the network first. However, internal/private networks are not completely immune to DoS attacks. Attackers can still launch DoS attacks against internal networks by exploiting vulnerabilities in the network infrastructure, such as routers or switches. Additionally, insiders with authorised access to the network can also launch DoS attacks, making it crucial to implement proper security measures and access controls.

In summary, public networks are more vulnerable to DoS attacks compared to internal/private networks due to their accessibility to anyone with an internet connection. However, internal/private networks are not completely immune to DoS attacks, and proper security measures and access controls are necessary to mitigate this risk. It is important for organisations to implement robust security measures and practices to protect both public and internal/private networks from DoS attacks and other security threats.