Design Resilient Architectures 30% Flashcards
An online media company has created an application which provides analytical data to its clients. The application is hosted on EC2 instances in an Auto Scaling Group. You have been brought on as a consultant and add an Application Load Balancer to front the Auto Scaling Group and distribute the load between the instances. The VPC which houses this architecture is running IPv4 and IPv6. The last thing you need to do to complete the configuration is point the domain name to the Application Load Balancer. Using Route 53, which record type at the zone apex will you use to point the DNS name of the Application Load Balancer? Choose two.
Alias with an A type record set.
Alias with a type “AAAA” record set and Alias with a type “A” record set are correct. To route domain traffic to an ELB load balancer, use Amazon Route 53 to create an alias record that points to your load balancer. An alias record is a Route 53 extension to DNS.
Alias with an AAAA type record set.
Alias with a type “AAAA” record set and Alias with a type “A” record set are correct. To route domain traffic to an ELB, use Amazon Route 53 to create an alias record that points to your load balancer.
Q: Your development team has created a gaming application that uses DynamoDB to store user statistics and provide fast game updates back to users. The team has begun testing the application but needs a consistent data set to perform tests with. The testing process alters the dataset, so the baseline data needs to be retrieved upon each new test. Which AWS service can meet this need by exporting data from DynamoDB and importing data into DynamoDB?
A: Elastic Map Reduce
You can use Amazon EMR with a customized version of Hive that includes connectivity to DynamoDB to perform operations on data stored in DynamoDB:
Loading DynamoDB data into the Hadoop Distributed File System (HDFS) and using it as input into an Amazon EMR cluster
Querying live DynamoDB data using SQL-like statements (HiveQL)
Joining data stored in DynamoDB and exporting it or querying against the joined data
Exporting data stored in DynamoDB to Amazon S3
Importing data stored in Amazon S3 to DynamoDB
Q: A new startup is considering the advantages of using DynamoDB versus a traditional relational database in AWS RDS. The NoSQL nature of DynamoDB presents a small learning curve to the team members who all have experience with traditional databases. The company will have multiple databases, and the decision will be made on a case-by-case basis. Which of the following use cases would favor DynamoDB? Select two.
A: Managing web session data
DynamoDB is a NoSQL database that supports key-value and document data structures. A key-value store is a database service that provides support for storing, querying, and updating collections of objects that are identified using a key and values that contain the actual content being stored. Meanwhile, a document data store provides support for storing, querying, and updating items in a document format such as JSON, XML, and HTML. DynamoDB’s fast and predictable performance characteristics make it a great match for handling session data. Plus, since it’s a fully-managed NoSQL database service, you avoid all the work of maintaining and operating a separate session store.
Q: A company has an application for sharing static content, such as photos. The popularity of the application has grown, and the company is now sharing content worldwide. This worldwide service has caused some issues with latency. What AWS services can be used to host a static website, serve content to globally dispersed users, and address latency issues, while keeping cost under control? Choose two.
A: S3
Amazon S3 is an object storage built to store and retrieve any amount of data from anywhere on the Internet. It’s a simple storage service that offers an extremely durable, highly available, and infinitely scalable data storage infrastructure at very low costs. AWS Global Accelerator and Amazon CloudFront are separate services that use the AWS global network and its edge locations around the world. CloudFront improves performance for both cacheable content (such as images and videos) and dynamic content (such as API acceleration and dynamic site delivery). Global Accelerator improves performance for a wide range of applications over TCP or UDP by proxying packets at the edge to applications running in one or more AWS Regions. Global Accelerator is a good fit for non-HTTP use cases, such as gaming (UDP), IoT (MQTT), or Voice over IP, as well as for HTTP use cases that specifically require static IP addresses or deterministic, fast regional failover. Both services integrate with AWS Shield for DDoS protection.
CloudFront
Amazon CloudFront is a fast content delivery network (CDN) service that securely delivers data, videos, applications, and APIs to customers globally with low latency, high transfer speeds, all within a developer-friendly environment. CloudFront is integrated with AWS – both physical locations that are directly connected to the AWS global infrastructure, as well as other AWS services. CloudFront works seamlessly with services including AWS Shield for DDoS mitigation, Amazon S3, Elastic Load Balancing, or Amazon EC2 as origins for your applications, and Lambda@Edge to run custom code closer to customers’ users and to customize the user experience. Lastly, if you use AWS origins such as Amazon S3, Amazon EC2, or Elastic Load Balancing, you don’t pay for any data transferred between these services and CloudFront.
Q: You are working as a Solutions Architect in a large healthcare organization. You have many Auto Scaling Groups that you need to create. One requirement is that you need to reuse some software licenses and therefore need to use dedicated hosts on EC2 instances in your Auto Scaling Groups. What step must you take to meet this requirement?
A: Use a launch template with your Auto Scaling Group.
In addition to the features of Amazon EC2 Auto Scaling that you can configure by using launch templates, launch templates provide more advanced Amazon EC2 configuration options. For example, you must use launch templates to use Amazon EC2 Dedicated Hosts. Dedicated Hosts are physical servers with EC2 instance capacity that are dedicated to your use. While Amazon EC2 Dedicated Instances also run on dedicated hardware, the advantage of using Dedicated Hosts over Dedicated Instances is that you can bring eligible software licenses from external vendors and use them on EC2 instances. If you currently use launch configurations, you can specify a launch template when you update an Auto Scaling group that was created using a launch configuration. To create a launch template to use with an Auto Scaling Group, create the template from scratch, create a new version of an existing template, or copy the parameters from a launch configuration, running instance, or other template.
Q: Your company has recently converted to a hybrid cloud environment and will slowly be migrating to a fully AWS cloud environment. The AWS side is in need of some steps to prepare for disaster recovery. A disaster recovery plan needs drawn up and disaster recovery drills need to be performed for compliance reasons. The company wants to establish Recovery Time and Recovery Point Objectives. The RTO and RPO can be pretty relaxed. The main point is to have a plan in place, with as much cost savings as possible. Which AWS disaster recovery pattern will best meet these requirements?
A: Backup and restore
This is the least expensive option and cost is the overriding factor.
Q: A gaming company is creating an application which simply provides a leaderboard for specific games. The leaderboard will use DynamoDB for data, and simply needs to be updated in near real-time. An EC2 instance will be configured to house the application which will be accessed by subscribers from the Internet. Which step is NOT necessary for internet traffic to flow to and from the Internet?
A: A route in the route table to the DynamoDB table.
The application needs to be able to communicate with the DynamoDB table, but this has nothing to do with the necessary steps for internet traffic flow to and from the application instance.
Q: Your organization uses AWS CodeDeploy for deployments. Now you are starting a project on the AWS Lambda platform. For your deployments, you’ve been given a requirement of performing blue-green deployments. When you perform deployments, you want to split traffic, sending a small percentage of the traffic to the new version of your application. Which deployment configuration will allow this splitting of traffic?
A: Canary
Correct. With canary, traffic is shifted in two increments. You can choose from predefined canary options that specify the percentage of traffic shifted to your updated Lambda function version in the first increment and the interval, in minutes, before the remaining traffic is shifted in the second increment.
Q: A database outage has been very costly to your organization. You have been tasked with configuring a more highly-available architecture. The main requirement is that the chosen architecture needs to meet an aggressive RTO in case of disaster. You have decided to use an RDS Multi-AZ deployment. How is the replication handled for RDS Multi-AZ?
A: Amazon RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone.
Amazon RDS provides high availability and failover support for DB instances using Multi-AZ deployments. Amazon RDS uses several different technologies to provide failover support. Multi-AZ deployments for MariaDB, MySQL, Oracle, and PostgreSQL DB instances use Amazon’s failover technology. SQL Server DB instances use SQL Server Database Mirroring (DBM) or Always On Availability Groups (AGs). In a Multi-AZ deployment, Amazon RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone. The primary DB instance is synchronously replicated across Availability Zones to a standby replica to provide data redundancy, eliminate I/O freezes, and minimize latency spikes during system backups. Running a DB instance with high availability can enhance availability during planned system maintenance, and help protect your databases against DB instance failure and Availability Zone disruption.
Q: Your company is using a hybrid configuration because there are some legacy applications which are not easily converted and migrated to AWS. And with this configuration comes a typical scenario where the legacy apps must maintain the same private IP address and MAC address. You are attempting to convert the application to the cloud and have configured an EC2 instance to house the application. What you are currently testing is removing the ENI from the legacy instance and attaching it to the EC2 instance. You want to attempt a cold attach. What does this mean?
A: Attach ENI when the instance is being launched.
Best practices for configuring network interfaces You can attach a network interface to an instance when it’s running (hot attach), when it’s stopped (warm attach), or when the instance is being launched (cold attach). You can detach secondary network interfaces when the instance is running or stopped. However, you can’t detach the primary network interface. You can move a network interface from one instance to another, if the instances are in the same Availability Zone and VPC but in different subnets. When launching an instance using the CLI, API, or an SDK, you can specify the primary network interface and additional network interfaces. Launching an Amazon Linux or Windows Server instance with multiple network interfaces automatically configures interfaces, private IPv4 addresses, and route tables on the operating system of the instance. A warm or hot attach of an additional network interface may require you to manually bring up the second interface, configure the private IPv4 address, and modify the route table accordingly. Instances running Amazon Linux or Windows Server automatically recognize the warm or hot attach and configure themselves. Attaching another network interface to an instance (for example, a NIC teaming configuration) cannot be used as a method to increase or double the network bandwidth to or from the dual-homed instance. If you attach two or more network interfaces from the same subnet to an instance, you may encounter networking issues such as asymmetric routing. If possible, use a secondary private IPv4 address on the primary network interface instead. For more information, see Assigning a secondary private IPv4 address.
Q: Your company has recently converted to a hybrid cloud environment and will slowly be migrating to a fully AWS cloud environment. The AWS side is in need of some steps to prepare for disaster recovery. A disaster recovery plan needs drawn up and disaster recovery drills need to be performed. The company wants to establish Recovery Time and Recovery Point Objectives, with a major component being a very aggressive RTO, with cost not being a major factor. You have determined and will recommend that the best DR configuration to meet cost and RTO/RPO objectives will be to run a second AWS architecture in another Region in an active-active configuration. Which AWS disaster recovery pattern will best meet these requirements?
A: Multi-site
Correct. Multi-site with the active-active architecture is correct. This pattern will have the highest cost but the quickest failover.
Q: You are working for a large financial institution and preparing for disaster recovery and upcoming DR drills. A key component in the DR plan will be the MySQL database instances and their data. The Recovery Time Objective (RTO) is such that read replicas can be used to offload read traffic from the master database. Which items are key features of read replicas? Choose three answers.
A: You can create read replicas within AZ, cross-AZ, or cross-Region.
Read replicas can be within AZ, cross-AZ, or cross-Region.
Read replica can be manually promoted as a standalone database instance.
Amazon RDS uses the MariaDB, MySQL, Oracle, PostgreSQL, and Microsoft SQL Server DB engines’ built-in replication functionality to create a special type of DB instance called a read replica from a source DB instance. Updates made to the source DB instance are asynchronously copied to the read replica. You can reduce the load on your source DB instance by routing read queries from your applications to the read replica. Using read replicas, you can elastically scale out beyond the capacity constraints of a single DB instance for read-heavy database workloads.
You can have up to five read replicas per master, each with its own DNS endpoint.
Amazon RDS uses the MariaDB, MySQL, Oracle, PostgreSQL, and Microsoft SQL Server DB engines’ built-in replication functionality to create a special type of DB instance called a read replica from a source DB instance. Updates made to the source DB instance are asynchronously copied to the read replica. You can reduce the load on your source DB instance by routing read queries from your applications to the read replica. Using read replicas, you can elastically scale out beyond the capacity constraints of a single DB instance for read-heavy database workloads.
Q: You work for an online retailer where any downtime at all can cause a significant loss of revenue. You have architected your application to be deployed on an Auto Scaling Group of EC2 instances behind a load balancer. You have configured and deployed these resources using a CloudFormation template. The Auto Scaling Group is configured with default settings, and a simple CPU utilization scaling policy. You have also set up multiple Availability Zones for high availability. The Load Balancer does health checks against an html file generated by script. When you begin performing load testing on your application and notice in CloudWatch that the load balancer is not sending traffic to one of your EC2 instances. What could be the problem?
A: The EC2 instance has failed the load balancer health check.
The load balancer will route the incoming requests only to the healthy instances. The EC2 instance may have passed status check and be considered health to the Auto Scaling Group, but the ELB may not use it if the ELB health check has not been met. The ELB health check has a default of 30 seconds between checks, and a default of 3 checks before making a decision. Therefore the instance could be visually available but unused for at least 90 seconds before the GUI would show it as failed. In CloudWatch where the issue was noticed it would appear to be a healthy EC2 instance but with no traffic. Which is what was observed.
Q: You are working for a large financial institution and preparing for disaster recovery and upcoming DR drills. A key component in the DR plan will be the database instances and their data. An aggressive Recovery Time Objective (RTO) dictates that the database needs to be synchronously replicated. Which configuration can meet this requirement?
A: RDS Multi-AZ
Amazon RDS Multi-AZ deployments provide enhanced availability and durability for RDS database (DB) instances, making them a natural fit for production database workloads. When you provision a Multi-AZ DB Instance, Amazon RDS automatically creates a primary DB Instance and synchronously replicates the data to a standby instance in a different Availability Zone (AZ). Each AZ runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable. In case of an infrastructure failure, Amazon RDS performs an automatic failover to the standby (or to a read replica in the case of Amazon Aurora), so that you can resume database operations as soon as the failover is complete. Since the endpoint for your DB Instance remains the same after a failover, your application can resume database operation without the need for manual administrative intervention.
Q: You have taken over management of several instances in the company AWS environment. You want to quickly review scripts used to bootstrap the instances at runtime. A URL command can be used to do this. What can you append to the URL http://169.254.169.254/latest/ to retrieve this data?
A: user-data/
When you launch an instance in Amazon EC2, you have the option of passing user data to the instance that can be used to perform common automated configuration tasks and even run scripts after the instance starts. You can pass two types of user data to Amazon EC2: shell scripts and cloud-init directives.
When you launch an instance in Amazon EC2, you have the option of passing user data to the instance that can be used to perform common automated configuration tasks and even run scripts after the instance starts. You can pass two types of user data to Amazon EC2: shell scripts and cloud-init directives.
A software company has created an application to capture service requests from users and also enhancement requests. The application is deployed on an Auto Scaling Group of EC2 instances fronted by an Application Load Balancer. The Auto Scaling Group has scaled to maximum capacity, but there are still requests being lost. The company has decided to use SQS with the Auto Scaling Group to ensure all messages are saved and processed. What is an appropriate metric for auto scaling with SQS?
backlog per instance
The issue with using a CloudWatch Amazon SQS metric like ApproximateNumberOfMessagesVisible for target tracking is that the number of messages in the queue might not change proportionally to the size of the Auto Scaling Group that processes messages from the queue. That’s because the number of messages in your SQS queue does not solely define the number of instances needed. The number of instances in your Auto Scaling Group can be driven by multiple factors, including how long it takes to process a message and the acceptable amount of latency (queue delay). The solution is to use a backlog per instance metric with the target value being the acceptable backlog per instance to maintain. You can calculate these numbers as follows: Backlog per instance: To calculate your backlog per instance, start with the ApproximateNumberOfMessages queue attribute to determine the length of the SQS queue (number of messages available for retrieval from the queue). Divide that number by the fleet’s running capacity, which for an Auto Scaling Group is the number of instances in the InService state, to get the backlog per instance.
Your company is using a hybrid configuration because there are some legacy applications which are not easily converted and migrated to AWS. And with this configuration comes a typical scenario where the legacy apps must maintain the same private ip address and MAC address. You are attempting to convert the application to the Cloud and have configured an EC2 instance to house the application. What you are currently testing is removing the ENI from the legacy instance and attaching it to the EC2 instance. You want to attempt a warm attach. What does this mean?
Attach the ENI to an instance when it is stopped.
Some best practices for configuring network interfaces: You can attach a network interface to an instance when it’s running (hot attach), when it’s stopped (warm attach), or when the instance is being launched (cold attach). You can detach secondary network interfaces when the instance is running or stopped. However, you can’t detach the primary network interface. You can move a network interface from one instance to another, if the instances are in the same Availability Zone and VPC but in different subnets. When launching an instance using the CLI, API, or an SDK, you can specify the primary network interface and additional network interfaces. Launching an Amazon Linux or Windows Server instance with multiple network interfaces automatically configures interfaces, private IPv4 addresses, and route tables on the operating system of the instance. A warm or hot attach of an additional network interface may require you to manually bring up the second interface, configure the private IPv4 address, and modify the route table accordingly. Instances running Amazon Linux or Windows Server automatically recognize the warm or hot attach and configure themselves. Attaching another network interface to an instance (for example, a NIC teaming configuration) cannot be used as a method to increase or double the network bandwidth to or from the dual-homed instance. If you attach two or more network interfaces from the same subnet to an instance, you may encounter networking issues such as asymmetric routing. If possible, use a secondary private IPv4 address on the primary network interface instead. For more information, see Assigning a secondary private IPv4 address.
A company has an Auto Scaling Group of EC2 instances hosting their retail sales application. Any significant downtime for this application can result in large losses of profit. Therefore the architecture also includes an Application Load Balancer and an RDS database in a Multi-AZ deployment. What will happen to preserve high availability if the primary database fails?
The CNAME is switched from the primary db instance to the secondary.
Correct: Amazon RDS Multi-AZ deployments provide enhanced availability and durability for RDS database (DB) instances, making them a natural fit for production database workloads. When you provision a Multi-AZ DB Instance, Amazon RDS automatically creates a primary DB Instance and synchronously replicates the data to a standby instance in a different Availability Zone (AZ). Each AZ runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable. In case of an infrastructure failure, Amazon RDS performs an automatic failover to the standby (or to a read replica in the case of Amazon Aurora), so that you can resume database operations as soon as the failover is complete. Since the endpoint for your DB Instance remains the same after a failover, your application can resume database operation without the need for manual administrative intervention.
Failover is automatically handled by Amazon RDS so that you can resume database operations as quickly as possible without administrative intervention. When failing over, Amazon RDS simply flips the canonical name record (CNAME) for your DB instance to point at the standby, which is in turn promoted to become the new primary.
Your company has performed a Disaster Recovery drill which failed to meet the Recovery Time Objective (RTO) desired by executive management. The failure was due in large part by the amount of time taken to restore proper functioning on the database side. You have given management a recommendation of implementing synchronous data replication for the RDS database to help meet the RTO. Which of these options can perform synchronous data replication in RDS?
RDS Multi-AZ
Correct. Amazon RDS Multi-AZ deployments provide enhanced availability and durability for RDS database (DB) instances, making them a natural fit for production database workloads. When you provision a Multi-AZ DB instance, Amazon RDS automatically creates a primary DB instance and synchronously replicates the data to a standby instance in a different Availability Zone (AZ). Each AZ runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable. In case of an infrastructure failure, Amazon RDS performs an automatic failover to the standby (or to a read replica in the case of Amazon Aurora), so that you can resume database operations as soon as the failover is complete. Since the endpoint for your DB instance remains the same after a failover, your application can resume database operation without the need for manual administrative intervention.
A company has an auto scaling group of EC2 instances hosting their retail sales application. Any significant downtime for this application can result in large losses of profit. Therefore the architecture also includes an Application Load Balancer and an RDS database in a Multi-AZ deployment. The company has a very aggressive Recovery Time Objective (RTO) in case of disaster. How long will a failover of an RDS database typically complete
one to two minutes
Q: What happens during Multi-AZ failover and how long does it take? Failover is automatically handled by Amazon RDS so that you can resume database operations as quickly as possible without administrative intervention. When failing over, Amazon RDS simply flips the canonical name record (CNAME) for your DB instance to point at the standby, which is in turn promoted to become the new primary. We encourage you to follow best practices and implement database connection retry at the application layer. Failovers, as defined by the interval between the detection of the failure on the primary and the resumption of transactions on the standby, typically complete within one to two minutes. Failover time can also be affected by whether large uncommitted transactions must be recovered; the use of adequately large instance types is recommended with Multi-AZ for best results. AWS also recommends the use of Provisioned IOPS with Multi-AZ instances for fast, predictable, and consistent throughput performance.
You have configured an Auto Scaling Group of EC2 instances fronted by an Application Load Balancer. The back-end database is a MySQL RDS database. Your dev team has created a new AMI which has been hardened to meet company security standards, and this AMI needs to be deployed on all EC2 instances in the organization. What step or steps do you need to take to deploy this AMI?
Replace the launch configuration by a launch template using the new AMI.
AWS recommends that you create Auto Scaling groups from launch templates to ensure that you’re accessing the latest features and improvements. If you plan to continue to use launch configurations with Amazon EC2 Auto Scaling, be aware that not all Auto Scaling group features are available. When you edit an Auto Scaling group that has an existing launch configuration, you have the option of replacing the launch configuration with a launch template. This lets you use launch templates with any Auto Scaling groups that you currently use. In doing so, you can take advantage of the versioning and other features of launch templates
You have several EC2 instances in an auto scaling group fronted by a network load balancer. The instances will need access to S3 and DynamoDB. The auto scaling group was created from a launch template. What needs to be configured in the launch template to enable newly launched instances access to S3 and DynamoDB?
An IAM Role attached to newly launched instances with permissions to S3 and DynamoDB.
Correct. IAM roles are designed so that your applications can securely make API requests from your instances, without requiring you to manage the security credentials that the applications use. Instead of creating and distributing your AWS credentials, you can delegate permission to make API requests using IAM roles
You have two EC2 instances running in the same VPC, but in different subnets. You are removing the secondary ENI from an EC2 instance and attaching it to another EC2 instance. You want this to be fast and with limited disruption. So you want to attach the ENI to the EC2 instance when it’s running. What is this called?
hot attach
Correct. Here are some best practices for configuring network interfaces. You can attach a network interface to an instance when it’s running (hot attach), when it’s stopped (warm attach), or when the instance is being launched (cold attach). You can detach secondary network interfaces when the instance is running or stopped. However, you can’t detach the primary network interface. You can move a network interface from one instance to another if the instances are in the same Availability Zone and VPC but in different subnets. When launching an instance using the CLI, API, or an SDK, you can specify the primary network interface and additional network interfaces. Launching an Amazon Linux or Windows Server instance with multiple network interfaces automatically configures interfaces, private IPv4 addresses, and route tables on the operating system of the instance. A warm or hot attach of an additional network interface may require you to manually bring up the second interface, configure the private IPv4 address, and modify the route table accordingly. Instances running Amazon Linux or Windows Server automatically recognize the warm or hot attach and configure themselves. Attaching another network interface to an instance (for example, a NIC teaming configuration) cannot be used as a method to increase or double the network bandwidth to or from the dual-homed instance. If you attach two or more network interfaces from the same subnet to an instance, you may encounter networking issues such as asymmetric routing. If possible, use a secondary private IPv4 address on the primary network interface instead. For more information, see Assigning a secondary private IPv4 address.
An online cryptocurrency exchange platform is hosted in AWS which uses ECS Cluster and RDS in Multi-AZ Deployments configuration. The application is heavily using the RDS instance to process complex read and write database operations. To maintain the reliability, availability, and performance of your systems, you have to closely monitor how the different processes or threads on a DB instance use the CPU, including the percentage of the CPU bandwidth and total memory consumed by each process.
Which of the following is the most suitable solution to properly monitor your database?
enable Enhanced Monitoring in RDS
