To answer this question, we need to understand what graceful degradation means in the context of a denial-of-service (DoS) attack. Graceful degradation refers to the ability of software to continue functioning, albeit at a reduced capacity or performance, when faced with an attack or failure.
Let's go through each option to understand why it is correct or incorrect:
Option A) Fail-over to a higher-availability service - This option is incorrect. Fail-over to a higher-availability service typically refers to redirecting traffic to a backup system or server, which may not be possible during a DoS attack.
Option B) Vary its response times to subsequent requests - This option is correct. Software can exhibit graceful degradation by intentionally varying its response times to subsequent requests during a DoS attack. By slowing down response times, the software can prioritize legitimate requests and reduce the impact of the attack.
Option C) Disconnect the affected connectivity point - This option is incorrect. Disconnecting the affected connectivity point may help isolate the attack, but it doesn't directly exhibit graceful degradation.
Option D) Fail-over to a hot standby - This option is incorrect. Failing over to a hot standby is a form of redundancy where a backup system takes over when the primary system fails. It doesn't directly exhibit graceful degradation in response to a DoS attack.
The correct answer is Option B. This option is correct because varying the response times to subsequent requests allows the software to prioritize legitimate requests and continue functioning, albeit at a reduced capacity or performance, during a DoS attack.