AWS Certified Solutions Architect Associate (SAA02) – Free Practice Tests

Explanation

S3 Event Notifications can be set up on objects stored in S3. An event could be set up to notify when a delete is performed. Logging is turned off by default but can be enabled. When enabled, they can track requests to your S3 bucket.

S3 Server Access Logging tracks detailed information not currently available with CloudWatch metrics or CloudTrail logs. To track requests for access to your bucket, you can enable access logging. Each access log record provides details about a single access request, such as the requester, bucket name, request time, request action, response status, and error code, if any. Access log information can be useful in security and access audits. It can also help you learn about your customer base and understand your Amazon S3 bill.

Explanation

An Elastic Load Balancer(ELB) by default, routes each request independently to the application instance with the smallest load. However, you can use the sticky session feature (also known as session affinity), which enables the load balancer to bind a user’s session to a specific application instance. This ensures that all requests coming from the user during the session will be sent to the same application instance. The key to managing the sticky session is determining how long your load balancer should consistently route the user’s request to the same application instance. If your application has its own session cookie, then you can set Elastic Load Balancing to create the session cookie to follow the duration specified by the application’s session cookie. If your application does not have its own session cookie, then you can set Elastic Load Balancing to create a session cookie by specifying your own stickiness duration. You can associate stickiness duration for only HTTP/HTTPS load balancer listeners. An application instance must always receive and send two cookies: A cookie that defines the stickiness duration and a special Elastic Load Balancing cookie named AWSELB, that has the mapping to the application instance.

Explanation

You can place a network interface on each of your web servers that connects to a mid-tier network where an application server resides. The application server can also be dual-homed to a back-end network (subnet) where the database server resides. Instead of routing network packets through the dual-homed instances, each dual-homed instance receives and processes requests on the front end, initiates a connection to the back end, and then sends requests to the servers on the back-end network.

Explanation

Amazon RDS Read Replicas provide enhanced performance and durability for database (DB) instances. This replication feature makes it easy to elastically scale out beyond the capacity constraints of a single DB Instance for read-heavy database workloads. You can create one or more replicas of a given source DB Instance and serve high-volume application read traffic from multiple copies of your data, thereby increasing aggregate read throughput. Read replicas can also be promoted when needed to become standalone DB instances.

Read replicas in different regions are available in Amazon RDS for MYSQL, MariaDB, PostgreSQL, Oracle, and Aurora

Explanation

All traffic should be routed via Internet Gateway. So, a route should be created with 0.0.0.0/0 as a source, and your Internet Gateway as your target.

Explanation

Amazon Redshift applies changes to a cluster security group immediately. So if you have associated the cluster security group with a cluster, inbound cluster access rules in the updated cluster security group apply immediately.

Explanation

Explanation

To better control scale-out events, you can create a step scaling policy that dictates different levels of scaling based on different utilization levels of a metric you’ve selected.

Adjusting the cooldown period also minimizes the likelihood of scaling out again before the instances that were deployed in a previous scale out event have had time to warm up and handle requests to their full capability.

Explanation

Amazon Relational Database Service (Amazon RDS) is a web service that makes it easier to set up, operate, and scale a relational database in the cloud. It provides cost-efficient, resizeable capacity for an industry-standard relational database and manages common database administration tasks. There are several ways you can track the performance and health of a database or a DB instance. You can: Use the free Amazon CloudWatch service to monitor the performance and health of a DB instance. Subscribe to Amazon RDS events to be notified when changes occur with a DB instance, DB snapshot, DB parameter group, or DB security group.View, download, or watch database log files using the Amazon RDS console or Amazon RDS APIs. You can also query some database log files that are loaded into database tables. Use the AWS CloudTrail service to record AWS calls made by your AWS account. The calls are recorded in log files and stored in an Amazon S3 bucket.

Explanation

STS is the “glue” that supports temporary access credentials for federation. If you are running code, AWS CLI, or Tools for Windows PowerShell commands inside an EC2 instance, you can take advantage of roles for Amazon EC2. Otherwise, you can call an AWS STS API to get the temporary credentials, and then use them explicitly to make calls to AWS services.

Explanation

The Simple Monthly Calculator is used to calculate projected costs, assuming you know what AWS resources you’ll be consuming.

Explanation

When you create a default VPC, the following components are created with it:

Explanation

You grant AWS Lambda permission to access a DynamoDB Stream using an IAM role known as the “execution role”.

Explanation

If you stop the instances you will not be charged and the data will still be kept. If you terminate the instances you will lose all your data. If you take a snapshot of all the instances and then terminate all the instances you will not be charged but will still have all your data in the snapshot which can be restored later.

Explanation

By tagging all resources with the business unit and enabling detailed billing reports, you would enable the finance team to run cost reports by business unit.

Explanation

AWS is responsible for what is known as Security ‘of’ the Cloud. This covers their global infrastructure elements – Regions, Availability Zones, and Edge Locations, and also the foundations of their services covering Compute, Storage, Database, and Network

Explanation

Auto Scaling is an AWS service that allows you to increase or decrease the number of EC2 instances within your application’s architecture. With Auto Scaling, you create collections of EC2 instances, called Auto Scaling groups. You can create these groups from scratch, or from existing EC2 instances that are already in production

Explanation

Most of these choices improve the responsiveness of CloudWatch in some way, but the aspect of this question is improving the responsiveness of CloudWatch alarms you have already implemented. This means you are not interested in additional metric information outside of the custom metrics you’ve already created in CloudWatch, and any features that increase responsiveness to metrics other than what you want will not be beneficial.

So, creating CloudWatch Log metric filters for default RDS metrics will not help, even though this can provide 1-second granularity, it is unlikely the logs will indicate overall latency and throughput of reads and writes, as these performance metrics are not related to specific API calls, but rather general database performance.

Performance Insights allow you to review and analyze your RDS database performance overall, but is not ideal for identifying a performance issue in real-time.

Enabling Enhanced monitoring does provide increased insight into RDS database performance, and with the increased granularity of 5 seconds instead of 60 seconds, or potentially even 1-second granularity through CloudWatch Log Streams. However, Enhanced Monitoring provides specific operating system metrics and other performance metrics, and would not apply to the custom metric you have created using CloudWatch.

Enabling Detailed Monitoring will increase the delivery of average metrics from every 5 minutes to every minute, and this will apply to your custom metrics as well.

In addition, creating a Route 53 CloudWatch Alarm Health Check will monitor the transmission of data to CloudWatch, and can effectively alert you before the CloudWatch alarm is even triggered.

Explanation

OpsWorks stacks will let you utilize your existing Chef recipes, but only OpsWorks for Chef Automate will provide you with centralized, continuous configuration management.

Explanation

The user cannot authorize an Amazon EC2 security group if it is in a different AWS Region than the RDS DB instance. The user can authorize an IP range or specify an Amazon EC2 security group in the same region that refers to an IP address in another region. In this case allow IP of US West inside US East’s security group and open the RDS security group for US East region.

Explanation

These types of issues can be investigated in a checklist type manner. First, it’s important to verify manually that the EC2 instances are properly functioning. If so, it becomes a network issue. Are the Security Groups configured properly? Are the ACLs configured properly? Once the instances are verified, it is most likely that a Security Group or ACL is not configured properly.

Explanation

A Virtual Private Cloud (VPC) is a virtual network dedicated to the user’s AWS account. It enables the user to launch AWS resources into a virtual network that the user has defined. An Elastic Network Interface (ENI) is a virtual network interface that the user can attach to an instance in a VPC.

The ENI allows the user to change the security group of a running instance. Thus, in the present scenario when the organization wants to have a separate security group for one of the instances, it should change the security group of that ENI. This avoids the cost and time of deploying a new instance or configuring a new subnet, or changing the configuration of an existing security group.

Explanation

There are essentially three types of answers here – choices that use no automation, choices that use the incorrect type of automation given the situation, and a choice that uses the correct type of automation.

First, the choices that use little to no automation in this case would be the least recommended decision. Uploading millions of files to either Standard or Standard-IA and then waiting to review costs and access patterns could be very costly.

Second, the choice to use storage class analysis could work eventually, if you have the time to wait for analytics to be gathered (which could still be as costly as the choice above) and the time to then review the analytics, and then sift through the files to migrate them to the correct storage class. This is a better choice, but not the best choice.

Finally, the correct answer would be to use Intelligent_Tiering, which continuously monitors the access frequency and shifts the objects between a standard and infrequent-access tier depending on how access patterns may change. This happens automatically, and starts immediately, so it is the best choice of the options provided.

Explanation

In Hybrid cloud environment where connectivity between AWS and Corporate datacenter is critical, redundant active/active or active/passive configurations should be implemented for connectivity resources. redundancy has to be on both sides (AWS and On-premises) hence the minimum requirements to implement this architecture is two direct connect lines and two customer devices (ideally in two different data centers)

Explanation

Your VPC has an implicit router and a main route table that you can modify. Each subnet you create must be associated with a route table. Adding an internet gateway and adding a route to that IGW facilitates traffic out to the Internet for a public subnet. NAT instance and NAT gateways are provided to allow instances in private subnets to gain internet access

Explanation

You restrict access to Amazon S3 content by creating an origin access identity, which is a special CloudFront user. You change Amazon S3 permissions to give the origin access identity permission to access your objects, and to remove permissions from everyone else. When your users access your Amazon S3 objects using CloudFront URLs, the CloudFront origin access identity gets the objects on your users’ behalf. If your users try to access objects using Amazon S3 URLs, they’re denied access. The origin access identity has permission to access objects in your Amazon S3 bucket, but users don’t.

Explanation

An application load balancer configured to use the HTTPS or SSL protocol with back-end authentication enabled fails public key authentication it’s probable that the public key on the SSL certificate does not match the public key configured on the load balancer. You might need to update your SSL certificate. If your SSL certificate is current, try re-installing it on your load balancer.

Explanation

Amazon S3 supports several mechanisms that give you flexibility to control who can access your data as well as how, when, and where they can access it. Amazon S3 provides four different access control mechanisms: AWS Identity and Access Management (IAM) policies, Access Control Lists (ACLs), bucket policies, and query string authentication. IAM enables organizationsto create and manage multiple users under a single AWS account. With IAM policies, you can grant IAM users fine-grained control to your Amazon S3 bucket or objects. You can use ACLs to selectively add (grant) certain permissions on individual objects. Amazon S3 bucket policies can be used to add or deny permissions across some or all of the objects within a single bucket. With Query string authentication, you have the ability to share Amazon S3 objects through URLs that are valid for a specified period of time.

Explanation

Your VPC automatically comes with a modifiable default Network ACL. By default, it allows all inbound and outbound IPv4 traffic and, if applicable, IPv6 traffic. You can create a custom Network ACL and associate it with a subnet. By default, each custom Network ACL denies all inbound and outbound traffic until you add rules. Each subnet in your VPC must be associated with a network ACL. If you don’t explicitly associate a subnet with a network ACL, the subnet is automatically associated with the default network ACL.

AWS WAF could meet the same security requirements, but would add considerably more cost to your overall budget

Explanation

Amazon Glacier and S3 Standard-IA are both designed for storing infrequently accessed data. This is why the data storage fees are roughly one-half to one-sixth the cost of Standard Storage. Retrieval fees will quickly add up if the data is retrieved too often, so planning or correctly setting your object lifecycle based on how often you or your company will need the data is important.

Explanation

Amazon Simple Email Service (Amazon SES) is a highly scalable and cost-effective email-sending service for businesses and developers. It integrates with other AWS services, making it easy to send emails from applications that are hosted on AWS.

Explanation

Amazon Redshift is a fast, fully managed data warehouse that makes it simple and cost-effective to analyze all your data using standard SQL and your existing Business Intelligence (BI) tools. It allows you to run complex analytic queries against petabytes of structured data, using sophisticated query optimization, columnar storage on high-performance local disks, and massively parallel query execution.

Explanation

The Elastic Load Balancer can integrate with the AWS Certificate Manager to provide a central method of managing your TLS/SSL certificates. It allows you to renew, deploy and configure your TLS/SSL certificates for your application or website from a single location.

Explanation

With IAM, you can centrally manage users, security credentials such as access keys, and permissions that control which AWS resources users can access. In some cases, you might have an IAM user with full access to IAM and Amazon S3. If the IAM user assigns a bucket policy to an Amazon S3 bucket and doesn’t specify the root user as a principal, the root user is denied access to that bucket. However, as the root user, you can still access the bucket by modifying the bucket policy to allow root user access.

Explanation

SQS provides several advantages over building your own software for managing message queues that require significant up-front time for development and configuration. Homegrown solutions require ongoing hardware maintenance and system administration resources. The complexity of configuring and managing these systems is compounded by the need for redundant storage of messages that ensures messages are not lost if hardware fails. In contrast, Amazon SQS requires no administrative overhead and little configuration. SQS works on a massive scale, processing billions of messages per day. You can scale the amount of traffic you send to Amazon SQS up or down without any configuration. Amazon SQS also provides extremely high message durability.

Explanation

Amazon Simple Queue Service (SQS) is a highly reliable distributed messaging system for storing messages as they travel between computers. By using Amazon SQS, developers can simply move data between distributed application components. It is used to achieve compartmentalization or loose coupling. In this case all the modules will send a message to the logger queue and the data will be processed by queue as per the resource availability.

Explanation

Regarding Amazon Route 53, if your application is running on Amazon EC2 instances in two or more Amazon EC2 regions, and if you have more than one Amazon EC2 instance in one or more regions, you can use latency-based routing to route traffic to the correct region and then use weighted resource record sets to route traffic to instances within the region based on weights that you specify

Explanation

You can use snapshots to increase the size of EBS volumes. Take a snapshot of the existing volume, create a new volume from the snapshot but with a larger size, then replace the original snapshot with the new volume. There is a performance hit with new volumes because, while the volume is created immediately, the data is lazy loaded. So there will be a first time performance hit when accessing each block on the volume. This problem can be resolved by initializing the volume and accessing each block one time before the volume is put into service.

Explanation

The key benefit of launch templates is their capability to support multiple instance types and purchase types within the same template.

Explanation

Amazon S3 storage offers very high durability, but it is still a best practice to protect against user level deletion or overwriting of data using versioning, cross-region replication, and MFA Delete.

Explanation

Versioning provides redundancy as it keeps multiple variants of an object in the same bucket. You can use versioning to preserve, retrieve, and restore every version of every object stored in your Amazon S3 bucket. With versioning, you can easily recover from both unintended user actions and application failures.

Explanation

After you turn on S3 Transfer Acceleration for a bucket, two new endpoints are created for the bucket: one for IPv4 and one for IPv6. You can use either the accelerate endpoints or the standard endpoints if you choose not to use the accelerate feature.

Explanation

Amazon S3 storage offers very high durability, but it is still a best practice to protect against user level deletion or overwriting of data using versioning, cross-region replication, and MFA Delete.

Explanation

The conditions section of a CloudFormation template defines conditions that control whether certain resources are created or whether certain resource properties are assigned a value during stack creation or update. For example, you could conditionally create a resource that depends on whether the stack is for a production or test environment

Explanation

For protecting the Amazon EBS data at REST, the user can use options, such as Data Encryption (Windows / Linux / third party based), Data Replication (AWS internally replicates data for redundancy), and Data Snapshot (for point in time backup). Reference: http://media.amazonwebservices.com/AWS_Security_Best_Practices.pdf

Explanation

Elastic Load Balancing supports both Internet Protocol version 6 (IPv6) and Internet Protocol version 4 (IPv4). Clients can connect to the user’s load balancer using either IPv4 or IPv6 (in EC2-Classic) DNS. However, communication between the load balancer and its back-end instances uses only IPv4. The user can use the Dualstack-prefixed DNS name to enable IPv6 supportfor communications between the client and the load balancers. Thus, the clients are able to access the load balancer using either IPv4 or IPv6 as their individual connectivity needs dictate.

Explanation

By launching your instances into a VPC instead of EC2-Classic, you gain the ability to: Assign static private IP addresses to your instances that persist across starts andstops Assign multiple IP addresses to your instances. Define network interfaces, and attach one or more network interfaces to your instances Change security group membership for your instances while they’re running Control the outbound traffic from your instances (egress filtering) in addition to controlling the inbound traffic to them (ingress filtering). Add an additional layer of access control to your instances in the form of network access control lists (ACL). Run your instances on single-tenant hardware

Explanation

SQS allows you to quickly build hosted and scalable message queuing applications that can run on any computer. SQS stores messages in transit between diverse, distributed application components without losing messages and without requiring each component to be always available

Explanation

An EBS volume is off-instance storage that can persist independently from the life of an instance. You continue to pay for the volume usage as long as the data persists. EBS instances can be stopped and re-started. And EBS volumes boot faster than instance store volumes often by an order of magnitude

Explanation

Amazon RDS detects and automatically recovers from the most common failure scenarios for Multi-AZ deployments so that you can resume database operations as quickly as possible without administrative intervention. Amazon RDS automatically performs a failover in the event of any of the following:

• Loss of availability in primary Availability Zone
• Loss of network connectivity to primary
• Compute unit failure on primary
• Storage failure on primary

Explanation

For increased security, AWS recommends that you configure multi-factor authentication (MFA) to help protect your AWS resources. MFA adds extra security because it requires users to enter a unique authentication code from an approved authentication device or SMS text message when they access AWS websites or services. This type of MFA requires you to assign an MFA device (hardware or virtual) to the IAM user or the AWS root account.

Explanation

The charge for successful Requester Pays requests is straightforward: the requester pays for the data transfer and the request; the bucket owner pays for the data storage. However, the bucket owner is charged for the anonymous request.

Explanation

In AWS, ephemeral storage is only temporary storage. If the instance is stopped and started back all the data on ephemeral storage will be lost.

Explanation

You can secure your VPC instances using only security groups; however, you can add NACLs as a second layer of defense. Security groups — Act as a firewall for associated Amazon EC2 instances, controlling both inbound and outbound traffic at the instance level .  Network access control lists (NACLs) — Act as a firewall for associated subnets, controlling both inbound and outbound traffic at the subnet level . Security Groups supports allow rules only while Network Access Control Lists support allow and deny rules.

Explanation

If you get an InsufficientInstanceCapacity error when you try to launch an instance or start a stopped instance, AWS does not currently have enough available capacity to service your request. In this situation, reserved instances offer the required reliability to avoid outages and loss of money. Reserved Instances are a long-term capacity reservation, and you will not have to rely on Amazon having enough on-demand capacity. Usually these capacity issues are short term, but due to the nature of the company even short outages can be very costly.

Explanation

An Elastic Load Balancer(ELB) by default, routes each request independently to the application instance with the smallest load. However, you can use the sticky session feature (also known as session affinity), which enables the load balancer to bind a user’s session to a specific application instance. This ensures that all requests coming from the user during the session will be sent to the same application instance. The key to managing the sticky session is determining how long your load balancer should consistently route the user’s request to the same application instance. If your application has its own session cookie, then you can set Elastic Load Balancing to create the session cookie to follow the duration specified by the application’s session cookie. If your application does not have its own session cookie, then you can set Elastic Load Balancing to create a session cookie by specifying your own stickiness duration. You can associate stickiness duration for only HTTP/HTTPS load balancer listeners. An application instance must always receive and send two cookies: A cookie that defines the stickiness duration and a special Elastic Load Balancing cookie named AWSELB, that has the mapping to the application instance.

Explanation

Amazon EC2 allows you to set up and configure everything about your instances from your operating system up to your applications. An Amazon Machine Image (AMI) is simply a packaged-up environment that includes all the necessary bits to set up and boot your instance. M1 and M3 Standard instances have the same ratio of CPU and memory, some reasons below as to why you would use one over the other. M3 instances provide better, more consistent performance that M1 instances for most use-cases. M3 instances also offer SSD-based instance storage that delivers higher I/O performance. M3 instances are also less expensive than M1 instances. Due to these reasons, we recommend M3 for applications that require general purpose instances with a balance of compute, memory, and network resources. However, if you need more disk storage than what is provided in M3 instances, you may still find M1 instances useful for running your applications

Explanation

In AWS CloudFormation, Amazon EC2 resources that support the tagging feature can also be tagged in an AWS template. The tag values can refer to template parameters, other resource names, resource attribute values (e.g. addresses), or values computed by simple functions (e.g., a concatenated list of strings).

Explanation

To host a static website, the user needs to configure an Amazon S3 bucket for website hosting and then upload the website contents to the bucket. The website is then available at the region-specific website endpoint of the bucket.

If the user has an index.html object as part of the bucket, the user can always host it without the website hosting feature. However, it will require an absolute URL of the object. In this case the user can access the whole bucket as a website and need not refer individual objects separately.

Explanation

You can use AWS Identity and Access Management (IAM) roles and AWS Security and Token Service (STS) to set up cross-account access between AWS accounts. When you assume an IAM role in another AWS account to obtain cross-account access to services and resources in that account, AWS Cloudtrail logs the cross-account activity.

Explanation

Since the database is not located in the same location as the application servers, network latency and bandwidth could potentially be an issue

Explanation

Amazon SQS is a distributed queuing system that is optimized for horizontal scalability, not for single-threaded sending or receiving speeds. A single client can send or receive Amazon SQS messages at a rate of about 5 to 50 messages per second. Higher receive performance can be achieved by requesting multiple messages (up to 10) in a single call. It may take several seconds before a message that has been to a queue is available to be received.

Explanation

OpsWorks stacks will let you utilize your existing Chef recipes, but only OpsWorks for Chef Automate will provide you with centralized, continuous configuration management.

Explanation

To handle a higher load in your database, you can vertically scale up your master database with a simple push of a button. There are currently over 18 instance sizes that you can choose from when resizing your RDS MySQL, PostgreSQL, MariaDB, Oracle, or Microsoft SQL Server instance. For Amazon Aurora, you have 5 memory-optimized instance sizes to choose from. There is minimal downtime when you are scaling up on a Multi-AZ environment because the standby database gets upgraded first, then failover will occur to the newly sized database. A Single-AZ instance will be unavailable during the scale operation

Explanation

Networking performance offered by the c4.8xlarge instance is 10 Gigabit

Explanation

S3 Event Notifications can be set up on objects stored in S3. An event could be set up to notify when a delete is performed. Logging is turned off by default but can be enabled. When enabled, they can track requests to your S3 bucket.

S3 Server Access Logging tracks detailed information not currently available with CloudWatch metrics or CloudTrail logs. To track requests for access to your bucket, you can enable access logging. Each access log record provides details about a single access request, such as the requester, bucket name, request time, request action, response status, and error code, if any. Access log information can be useful in security and access audits. It can also help you learn about your customer base and understand your Amazon S3 bill.

Explanation

AWS is responsible for what is known as Security ‘of’ the Cloud. This covers their global infrastructure elements – Regions, Availability Zones, and Edge Locations, and also the foundations of their services covering Compute, Storage, Database, and Network

Explanation

If you have multiple resources that perform the same function, for example, web servers or email servers, and you want Amazon Route 53 to route traffic only to the resources that are healthy, you can configure DNS failover by associating health checks with your resource record sets. If a health check determines that the underlying resource is unhealthy, Amazon Route 53 routes traffic away from the associated resource record set.

Explanation

A security group controls the access to a DB instance. It does so by allowing access to IP address ranges or Amazon EC2 instances that you specify. Amazon RDS uses DB security groups, VPC security groups, and EC2 security groups. In simple terms, a DB security group controls access to a DB instance that is not in a VPC, a VPC security group controls access to a DB instance inside a VPC, and an Amazon EC2 security group controls access to an EC2 instance and can be used with a DB instance.

Explanation

You can create a VPC Gateway Endpoint to allow resources within a VPC to connect to DynamoDB without network communication extending outside your own VPC.

Explanation

A Geolocation routing policy would allow Route 53 to route queries based upon the location of users. DynDNS is used to automatically update DNS records. EDNS0 can be used to improve the accuracy of geolocation routing, but is not a routing policy in and of itself. Region based is not a valid Route 53 routing policy type.

Explanation

If a IAM user is trying to perform some action on an object belonging to another AWS user’s bucket, S3 will verify whether the owner of the IAM user has given sufficient permission to him. It also verifies the policy for the bucket as well as the policy defined by the object owner.

Explanation

You can host a static website on Amazon S3. On a static website, individual web pages include static content. They may also contain client-side scripts. Because your storage on Amazon S3 is virtually unlimited you can scale infinitely. You also do not need to service dynamic content so a database is not needed.

Explanation

Application Load Balancer
You are charged for each hour or partial hour that an Application Load Balancer is running and the number of Load Balancer Capacity Units (LCU) used per hour.

Network Load Balancer
You are charged for each hour or partial hour that a Network Load Balancer is running and the number of Load Balancer Capacity Units (LCU) used by Network Load Balancer per hour.

Classic Load Balancer
You are charged for each hour or partial hour that a Classic Load Balancer is running and for each GB of data transferred through your load balancer.

Explanation

Amazon Route 53 lets you configure DNS failover in active-active, active-passive, and mixed configurations to improve the availability of your application. When you have more than one resource performing the same function, you can configure Amazon Route 53 to check the health of your resources and respond to DNS queries using only the healthy resources.

Another solution would be to assign an elastic IP address to the EC2 instance and have a backup instance running. In the event of failure, move the Elastic IP from the primary instance to the backup instance.