Which is a critical security feature enabled by SDN?The ability to physically secure network devicesCentralized network control enabling rapid response to threatsUse of traditional firewalls without modificationsReliance on manual security configurations

The critical security feature enabled by Software-Defined Networking (SDN) is centralized network control enabling rapid response to threats.

Here's why:

1. Centralized Control: SDN allows for centralized control of network devices. This means that instead of having to manually configure each device, you can manage them all from a central location. This makes it easier to implement changes and respond to threats quickly.

2. Rapid Response: Because you can control the entire network from one place, you can respond to threats more rapidly. If a security issue is detected, you can immediately implement changes to mitigate the threat across the entire network.

3. Flexibility: SDN also provides flexibility in terms of security. You can easily adjust security settings and controls based on the current threat landscape.

4. Automation: SDN allows for automation of security tasks. This can reduce the risk of human error and ensure that security measures are implemented consistently across the network.

So, while physical security of network devices and use of traditional firewalls are important aspects of network security, they are not specific features enabled by SDN. Similarly, reliance on manual security configurations is actually something that SDN helps to avoid.