Cloud Provider Y owns Cloud Y, which provides a set of cloud services, virtual servers and one physical server. Cloud Services A and B are hosted on Virtual Server A, which is hosted by Physical Server A. Physical Server A also hosts Virtual Server B, which hosts redundant implementations of Cloud Services A and B for load balancing purposes. Cloud Service Consumer A is accessing Cloud Service A located on Virtual Server A. Cloud Service Consumer B is accessing Cloud Service B located on Virtual Server B. Cloud Service Consumers A and B are both owned by Cloud Consumer X.
Cloud Consumer X has recently complained that Cloud Services A and B have become less available than what is guaranteed in their service level agreements (SLAs). Cloud Provider Y launches an investigation that reveals that Virtual Servers A and B have been subjected to denial of service attacks. This is confirmed as the cause of the decline in the availability of Cloud Services A and B.

Which of the following statements describes a solution that can increase the availability of Cloud Services A and B?

• A. Cloud Provider Y can introduce a single sign-on mechanism for Virtual Server A to mitigate denial of service threats. The automated scaling listener can then be implemented on VirtualServer B in order to limit the number of instances of Cloud Services A and B. This will prevent Virtual Server B from overloading due to denial of service attacks.
• B. Cloud Provider Y can implement a cloud bursting system, whereby Cloud Service A on Virtual Server B automatically takes the place of Cloud Service A on Virtual Server A when that service fails. Similarly,Cloud Service B on Virtual Server A can then automatically take the place of Cloud Service B on Virtual Server A when that service fails.
• C. Cloud Provider Y can move Cloud Service B to Virtual Server A, thereby positioning Virtual Server B as a redundant fallback server used when Virtual Server A is successfully attacked. Similarly, Cloud Provider Yean move Cloud Service A to Virtual Server B, so that Virtual Server A acts as a redundant fallback server for when Virtual Server B is successfully attacked.
• D. Cloud Provider Y can implement the identity and access management mechanism to mitigate denial of service attacks and can further implement the failover system mechanism (by introducing a redundant physical server with redundant virtual servers) so that when an attack is successful on a given virtual server, a redundant virtual server can take its place.

Cloud Provider Y owns Cloud Y, which provides a set of cloud services, virtual servers, and one physical server. Cloud Services A and B are hosted on Virtual Server A, which is hosted by Physical Server A. Physical Server A also hosts Virtual Server B, which hosts redundant implementations of Cloud Services A and B for load balancing purposes. Cloud Service Consumer A is accessing Cloud Service A located on Virtual Server A. Cloud Service Consumer B is accessing Cloud Service B located on Virtual Server B. Cloud Service Consumers A and B are both owned by Cloud Consumer X.
Cloud Consumer X has recently complained that Cloud Service A is becoming increasingly unreliable. Cloud Provider Y launches an investigation that reveals that Virtual Server A has been crashing sporadically due to successful malicious intermediary attacks where malicious service agents have been inserting harmful data into messages sent by Cloud Service Consumer A to Cloud Service A.

Which of the following statements describes a solution that can mitigate the malicious intermediary attacks that have been occurring on Virtual Server A - and - can further help prevent the same types of attacks from occurring on Virtual Server B?

• A. Cloud Provider Y can implement the identity and access management mechanism for Virtual Servers A and B by physically deploying this mechanism on Physical Server A and then further implementing the resource replication mechanism to propagate the identity and access management system across Virtual Servers A and B.
• B. Cloud Provider Y can implement the failover system mechanism by requiring that redundant copies of all service agents be deployed. This will reduce the chances of any one service agent performing malicious actions at runtime.
• C. Cloud Provider Y can implement the cloud-based security group mechanism that establishes a logical trust boundary that encompasses Virtual Servers A and B.
• D. Cloud Provider Y can implement the encryption and digital signatures mechanisms to protect the contents of messages from being augmented by malicious service agents.

Cloud Service Consumer A invokes Cloud Service A from Cloud X (owned by Cloud Provider X) (1). To fulfill the request from Cloud Service Consumer A, Cloud Service A needs to invoke Cloud Service B that resides on Cloud Y (owned by Cloud Provider Y) (2). After completing its processing, Cloud Service B sends a response to Cloud Service A (3). Cloud Service A verifies the response and then finally sends its response to Cloud Service Consumer A (4).

The guaranteed availability of the Cloud Service A implementation is 95% and the guaranteed availability of the Cloud Service B implementation is 95%. Which of the following statements accurately describes the actual availability that Cloud Service Consumer A can receive based on the described scenario?

• A. Cloud Service Consumer A benefits from redundant cloud service implementations, thereby
  increasing the guaranteed availability as follows:
  1 - (1 - (0.95 - 0.1))X (1 - (0.95 - 0.1)) = 0.9775 or 97.75%
• B. Because Cloud Service A acts as both a cloud service and cloud service consumer in order to
  process Cloud Service Consumer B's request message, Cloud Service A forms a dependency on
  Cloud Service B. As a result, the combined availability decreases, as follows:
  0.95 X 0.95 = 0.9025 or 90.25%
• C. Because Cloud Service Consumer A's response message is processed by two separate cloud
  services, the combined availability increases as follows:
  1 - (1 - 0.95) X (1 - 0.95) = 0.9975 or 99.75%
• D. As a result of the dependency formed by Cloud Service Aon Cloud Service B,the combined availability decreases significantly as follows:
  (0.95 X 0.95) - 0.1 = 0.8025 or 80.25%