Question #21
Your entire AWS infrastructure lives inside of one Amazon VPC. You have an Infrastructure monitoring application running on an Amazon instance in Availability Zone (AZ) A of the region, and another application instance running in AZ B. The monitoring application needs to make use of ICMP ping to confirm network reachability of the instance hosting the application.
Can you configure the security groups for these instances to only allow the ICMP ping to pass from the monitoring instance to the application instance and nothing else? If so how?
- A. No, two instances in two different AZ’s can’t talk directly to each other via ICMP ping as that protocol is not allowed across subnet (iebroadcast) boundaries
- B. Yes, both the monitoring instance and the application instance have to be a part of the same security group, and that security group needs to allow inbound ICMP
- C. Yes, the security group for the monitoring instance needs to allow outbound ICMP and the application instance’s security group needs to allow Inbound ICMP
- D. Yes, both the monitoring instance’s security group and the application instance’s security group need to
Correct Answer: C
Even though ICMP is not a connection-oriented protocol, Security Groups are stateful. “Security groups are stateful responses to allowed inbound traffic are allowed to flow outbound regardless of outbound rules, and vice versa”. http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_SecurityGroups.htmlQuestion #22
You have two Elastic Compute Cloud (EC2) instances inside a Virtual Private Cloud (VPC) in the same
Availability Zone (AZ) but in different subnets. One instance is running a database and the other instance an application that will interface with the database. You want to confirm that they can talk to each other for your application to work properly.
Which two things do we need to confirm in the VPC settings so that these EC2 instances can communicate inside the VPC? (Choose two.)
- A. A network ACL that allows communication between the two subnets.
- B. Both instances are the same instance class and using the same Key-pair.
- C. That the default route is set to a NAT instance or internet Gateway (IGW) for them to communicate.
- D. Security groups are set to allow the application host to talk to the database on the right port/protocol.
Correct Answer: AD
Question #23
Which services allow the customer to retain full administrative privileges of the underlying EC2 instances?
(Choose two.)
- A. Amazon Elastic Map Reduce
- B. Elastic Load Balancing
- C. AWS Elastic Beanstalk
- D. Amazon Elasticache
- E. Amazon Relational Database service
Correct Answer: AC
Only the below services provide Root level access
– EC2
– Elastic Beanstalk
– Elastic MapReduce Master Node
– OpsworkQuestion #24
You have a web-style application with a stateless but CPU and memory-intensive web tier running on a cc2
8xlarge EC2 instance inside of a VPC The instance when under load is having problems returning requests within the SLA as defined by your business The application maintains its state in a DynamoDB table, but the data tier is properly provisioned and responses are consistently fast.
How can you best resolve the issue of the application responses not meeting your SLA?
- A. Add another cc2 8xlarge application instance, and put both behind an Elastic Load Balancer
- B. Move the cc2 8xlarge to the same Availability Zone as the DynamoDB table
- C. Cache the database responses in ElastiCache for more rapid access
- D. Move the database from DynamoDB to RDS MySQL in scale-out read-replica configuration
Correct Answer: A
DynamoDB is automatically available across three facilities in an AWS Region. So moving in to a same AZ is not possible / necessary.
In this case the DB layer is not the issue, the EC2 8xlarge is the issue; so add another one with a ELB in-front of it.
See also: https://aws.amazon.com/dynamodb/faqs/
Question #25
You are managing a legacy application Inside VPC with hard coded IP addresses in its configuration.
Which two mechanisms will allow the application to failover to new instances without the need for reconfiguration? (Choose two.)
- A. Create an ELB to reroute traffic to a failover instance
- B. Create a secondary ENI that can be moved to a failover instance
- C. Use Route53 health checks to fail traffic over to a failover instance
- D. Assign a secondary private IP address to the primary ENIO that can be moved to a failover instance
Correct Answer: BD
