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

Explanation

EC2 instance store volumes can be added as additional volumes to certain EBS-backed EC2 Instance types. Any data on the instance store volumes persists as long as the instance is running, but this data is deleted when the instance is terminated or if it fails (such as if an underlying drive has issues).

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

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.

The default maximum number of Access Keys per user is 2

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

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

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

A route table contains a set of rules, called routes, that are used to determine where network traffic is directed.

Each subnet in your VPC must be associated with a route table; the table controls the routing for the subnet. A subnet can only be associated with one route table at a time, but you can associate multiple subnets with the same route table. When you add an Internet gateway, an egress-only Internet gateway, a virtual private gateway, a NAT device, a peering connection, or a VPC endpoint in your VPC, you must update the route table for any subnet that uses these gateways or connections.

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

Multipart uploads must be used for files greater than 5 GB. Cross-region replication is used to reduce latency by placing objects closer to users. This would address the issue of having users in different continents. Another use case for cross-region replication is to meet compliance requirements of storing backup data a certain distance from their origin.

Explanation

In AWS EC2, while configuring a security group, the user needs to specify the IP address in CIDR notation. The CIDR IP range 10.20.30.40/32 says it is for a single IP 10.20.30.40. If the user specifies the IP as 10.20.30.40 only, the security group will not accept and ask it in a CIDR format

Explanation

In the event of a disaster to your AWS infrastructure you should be able to quickly launch resources in Amazon Web Services (AWS) to ensure business continuity. The following are some key steps you should have in place for preparation: 1. Set up Amazon EC2 instances to replicate or mirror data. 2. Ensure that you have all supporting custom software packages available in AWS. 3. Create and maintain AMIs of key servers where fast recovery is required. 4. Regularly run these servers, test them, and apply any software updates and configuration changes. 5. Consider automating the provisioning of AWS resources.

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

Issues that are not first solved locally will not be solved by moving to the cloud. Moving to the cloud is not a silver bullet. If there are inherent problems in the existing architecture there is no guarantee that they will be solved by moving to the cloud. Try to resolve any issues locally before migrating your architecture (and its existing issues) to the cloud.

Explanation

You can reduce EC2 spend by migrating to reserved/spot instances, eliminating/shrinking unused resources, or consolidating AWS accounts (to qualify for volume discounts). The paying account’s use of consolidated billing can benefit from volume pricing discounts gained thru aggregate account usage.

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

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

When you create a VPC, you must specify a range of IPv4 addresses for the VPC in the form of a Classless Inter-Domain Routing (CIDR) block; for example, 10.0.0.0/16. The first four IP addresses and the last IP address in each subnet CIDR block are not available for you to use, and cannot be assigned to an instance. AWS reserves the first four addresses and the last address in a CIDR block, so be sure to subtract five to give the number of addresses in a CIDR block available for use

Explanation

Both Snowball and VM Import can be used to migrate VMs. Snowball mitigates any bandwidth issues that may occur when using VM Import with standard Internet connections.

Explanation

Cost Explorer, this is a useful and powerful tool within Billing and Cost Management. It allows you to view historical billing information in a graphical format giving you greater insight to your AWS spend. A valuable tool that can help to identify where you should be focusing your cost optimization efforts. It also can forecast your estimated spend up to two months ahead using existing data as a reference. If you can see that your estimated future bills are becoming too high, you have the time now to identify where you can make and initiate cost reduction mechanisms to help mitigate the risk.

Cost Explorer comes configured with three pre-defined views which are commonly used to analyze spending across your account:

1. Monthly Spend by Service view – this covers the current and previous two months and is grouped by AWS services
2. Monthly Spend by Linked Account View – this covers the current and previous two months and is grouped by linked accounts
3. Daily Spend view – this covers the daily spend over the previous sixty days

Explanation

Using IAM, you apply permissions to IAM users, groups, and roles by creating policies. You can create two types of IAM policies: Managed Policies and Inline Policies. Managed policies are standalone policies that you can attach to multiple users, groups, and roles in your AWS account. Managed policies apply only to identities (users, groups, and roles) – not resources. Inline policies are policies that you create and manage, and that are embedded directly into a single user, group, or role.

Explanation

Blue/green deployments resolve application unavailability during updates.

Explanation

AWS provides customers with a PCI-compliant environment and the necessary tools to secure their environment. PCI compliance falls very much in line with the shared responsibility model. But ultimately, it is the customers responsibility to build and maintain a PCI-compliant environment.

Explanation

Using IAM, you apply permissions to IAM users, groups, and roles by creating policies. You can create two types of IAM policies: Managed Policies and Inline Policies. Managed policies are standalone policies that you can attach to multiple users, groups, and roles in your AWS account. Managed policies apply only to identities (users, groups, and roles) – not resources. Inline policies are policies that you create and manage, and that are embedded directly into a single user, group, or role.

Explanation

AWS is responsible for the security of the cloud in general, in areas such data security and protection against IP spoofing. The customer is responsible for security in the cloud in areas such as data encryption, installing security patches on EC2 instances, and IAM best practices. It is very important to understand this concept to avoid any lapses in your security measures.

Explanation

On-premises data centers have costs associated with the servers, storage, networking, power, cooling, physical space, and IT labor required to support applications and services running in the production environment. For servers, these questions are most applicable: What is your average server utilization? How much do you overprovision for peak load? What is the cost of over-provisioning?

Explanation

An RDS database such as MySQL is a good choice as the back end for a web server. Amazon Redshift is often paired with RDS to offload Data Warehousing/Reporting traffic. DynamoDB is a good choice for managing session state, shopping cart data, or time-series data.

Explanation

A prolonged grace period and a larger number of instances will solve these issues. You can use scaling policies to increase or decrease the number of running EC2 instances in your group automatically to meet changing conditions. When the scaling policy is in effect, the Auto Scaling group adjusts the desired capacity of the group and launches or terminates the instances as needed. If you manually scale or scale on a schedule, you must adjust the desired capacity of the group for the changes to take effect.

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

You can create a VPC with an instance tenancy of dedicated to ensure that all instances launched into the VPC are dedicated instances. Alternatively, you can specify the tenancy of the instance during launch

Explanation

The user may want to stop the automated scaling processes on the Auto Scaling groups either to perform manual operations or during emergency situations. To perform this, the user can suspend one or more scaling processes at any time. When the process is suspended and the user changes the desired capacity, the changes will take effect, but Auto Scaling will not be executed. Thus, the scaling activity will not happen even though there is a difference between the desired capacity and the current capacity.

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

The TCO (Total Cost of Ownership) Calculator is used to calculate savings given information about the user’s current environment.

Explanation

AWS Storage Gateway enables applications that are clustered using Windows Server Failover Clustering (WSFC) to use the iSCSI initiator to access a gateway’s volumes. However, connecting multiple hosts to the same iSCSI target is not supported. When using Red Hat Enterprise Linux (RHEL), you use the iscsi-initiator-utils RPM package to connect to your gateway iSCSI targets (volumes or VTL devices).

Explanation

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

Explanation

There are some issues that could cause EC2 instances in a VPC to be unable to reach the Internet, including the following. An Internet Gateway must be attached to the VPC for a public subnet. Ingress and egress for Security Groups and Access Control Lists must be correct. EC2 instances in a private subnet need a NAT instance or a NAT Gateway, and for a NAT instance’s source/destination checks must be turned off. EC2 instances in a public subnet must have a route to the Internet Gateway in the route table

Explanation

You can set up a variety of failover configurations using Amazon Route 53 alias: weighted, latency, geolocation routing, and failover resource record sets. Active-active failover: Use this failover configuration when you want all of your resources to be available the majority of the time. When a resource becomes unavailable, Amazon Route 53 can detect that it’s unhealthy and stop including it when responding to queries. Active-passive failover: Use this failover configuration when you want a primary group of resources to be available the majority of the time and you want a secondary group of resources to be on standby in case all of the primary resources become unavailable. When responding to queries, Amazon Route 53 includes only the healthy primary resources. If allof the primary resources are unhealthy, Amazon Route 53 begins to include only the healthy secondary resources in response to DNS queries. Active-active-passive and other mixed configurations: You can combine alias and non-alias resource record sets to produce a variety of Amazon Route 53 behaviors.

Explanation

It is best practice to enable automatic backups and set the backup window to occur during the daily low in write IOPS. Amazon RDS creates automated backups of your DB instance during the backup window of your DB instance. Amazon RDS saves the automated backups of your DB instance according to the backup retention period that you specify. If necessary, you can recover your database to any point in time during the backup retention period.

Explanation

You can choose between three EBS volume types to best meet the needs of their workloads: General Purpose (SSD), Provisioned IOPS (SSD), and Magnetic. General Purpose (SSD) is the new, SSD-backed, general purpose EBS volume type that we recommend as the default choice for customers. General Purpose (SSD) volumes are suitable for a broad range of workloads, including small to medium sized databases, development and test environments, and boot volumes. Provisioned IOPS (SSD) volumes offer storage with consistent and low-latency performance, and are designed for I/O intensive applications such as large relational or NoSQL databases. Magnetic volumes provide the lowest cost per gigabyte of all EBS volume types. Magnetic volumes are ideal for workloads where data is accessed infrequently, and applications where the lowest storage cost is important

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

Backup and restore, as defined in the “Using Amazon Web Services for Disaster Recovery” white paper, is most like traditional off-site backup replication. You can leverage services such as Amazon S3 or Amazon Storage Gateway to provide a backup replication target and Amazon EC2 can be used to restore access to your applications. This strategy for disaster recovery is the slowest of all AWS DR strategies.

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

You can run Amazon RDS for Oracle under two different licensing models – “License Included” and “Bring-Your-Own-License (BYOL)”. In the “License Included” service model, you do not need separately purchased Oracle licenses; the Oracle Database software has been licensed by AWS.

Explanation

Lazy loading keeps the cache up to date based only on requests, which avoids filling up the cache needlessly, but if data is only written to the cache when there is a cache miss, data in the cache can become stale since there are no updates to the cache when data is changed in the database. This issue is addressed by using lazy loading in conjunction with write through, which adds data or updates data in the cache whenever data is written to the database. You may also use CloudFront to optimize your caching. By default, CloudFront doesn’t consider headers when caching your objects in edge locations. If your origin returns two objects and they differ only by the values in the request headers, CloudFront caches only one version of the object

Explanation

T2 instances are Burstable Performance Instances that provide a baseline level of CPU performance with the ability to burst above the baseline. The baseline performance and ability to burst are governed by CPU Credits. M4 instances are the latest generation of General Purpose Instances. This family provides a balance of compute, memory, and network resources, and it is a good choice for many applications. In this instance, the only option which provides for growth while keeping costs in check is to upgrade to reserved M4 instances on a long term 3 year contract.

Explanation

An instance store provides temporary block-level storage for your instance. This storage is located on disks that are physically attached to the host computer. Instance store is ideal for temporary storage of information that changes frequently, such as buffers, caches, scratch data, and other temporary content, or for data that is replicated across a fleet of instances, such as a load-balanced pool of web servers.

Data in the instance store is lost under the following circumstances:

• The underlying disk drive fails
• The instance stops
• The instance terminates

If the instance reboots (either intentionally or unintentionally) the data persists.

Explanation

Amazon Simple Notification Service (Amazon SNS) is a fast, flexible, and fully managed push messaging service. Amazon SNS can be used to make push notifications to mobile devices. Amazon SNS can deliver notifications by SMS text message or email to the Amazon Simple Queue Service (SQS) queues or to any HTTP endpoint. In this case user can use the SNS apis to send SMS.

Explanation

For internal communication between S3 and an application running on EC2 instance, you need two policies:

1. An IAM trust policy that allows the EC2 instance to assume a role
2. An IAM policy or S3 bucket policy that allows the role to get/put objects to the specific bucket

So, the kind of policies that control access to S3 bucket are either an IAM Policy or S3 Bucket Policy. The IAM trust policy is required, but it doesn’t control access to S3.

Explanation

The user may want to stop the automated scaling processes on the Auto Scaling groups either to perform manual operations or during emergency situations. To perform this, the user can suspend one or more scaling processes at any time. Once it is completed, the user can resume all the suspended processes.

Explanation

An archive is a durably stored block of information. You store your data in Amazon Glacier as archives. You may upload a single file as an archive, but your costs will be lower if you aggregate your data. TAR and ZIP are common formats that customers use to aggregate multiple files into a single file before uploading to Amazon Glacier. The total volume of data and number of archives you can store are unlimited. Individual Amazon Glacier archives can range in size from 1 byte to 40 terabytes. The largest archive that can be uploaded in a single upload request is 4 gigabytes. For items larger than 100 megabytes, customers should consider using the Multipart upload capability. Archives stored in Amazon Glacier are immutable, i.e. archives can be uploaded and deleted but cannot be edited or overwritten.

Explanation

As your needs change, you might find that your instance is over-utilized (the instance type is too small) or under-utilized (the instance type is too large). If the root device for your instance is an Elastic Block Store (EBS) volume, you can change the size of the instance simply by changing its instance type, which is known as resizing it. If the root device for your instance is an instance store volume, you must migrate your application to a new instance with the instance type that you want

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.

The default maximum number of Access Keys per user is 2

Explanation

The spot instances are ideal for the data processing workload during non-business hours, and deducting those instances from your minimum workload requirements leaves roughly six instances that are running all day. Purchase six standard reserved instances to meet this need with the greatest discount. You can then schedule reserved instances to run during business hours to meet the increase, and on-demand instances to scale as needed while providing necessary availability.

Explanation

In this case the alarm watches a metric every 5 minutes for 10 intervals. Thus, it needs at least 50 minutes to come to the “OK” state. Till then it will be in the INSUFFUCIENT_DATA state. Since 90 minutes have passed and CPU utilization is at 80% constant, the state of alarm will be “ALARM”.

Explanation

In certain scenarios, such as when flash traffic is expected, or in the case where a load test cannot be configured to gradually increase traffic, AWS recommends that you have your load balancer “pre-warmed”. They will configure the load balancer to have the appropriate level of capacity based on the traffic that you expect. They also need to know the start and end dates of your tests or expected flash traffic, the expected request rate per second and the total size of the typical request/response that you will be testing

Explanation

The key is that the requirement is for high availability at the web-tier. While multi-AZ deployments and cross-region replication can contribute to high availability, they are each at the storage tier. Route 53 with Health Checks and Failover, Elastic Load Balancer (with health checks and various forms of load balancing, and auto scaling groups create high availability at the web tier.

Explanation

Amazon VPC provides two features that you can use to increase security for your VPC: 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 (ACLs)–Act as a firewall for associated subnets, controlling both inbound and outbound traffic at the subnet level. Security groups are stateful: (Return traffic is automatically allowed, regardless of any rules) Network ACLs are stateless: (Return traffic must be explicitly allowed by rules)

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

With target tracking scaling policies, you select a scaling metric and set a target value. Amazon EC2 Auto Scaling creates and manages the CloudWatch alarms that trigger the scaling policy and calculates the scaling adjustment based on the metric and the target value. The scaling policy adds or removes capacity as required to keep the metric at, or close to, the specified target value. In addition to keeping the metric close to the target value, a target tracking scaling policy also adjusts to the changes in the metric due to a changing load pattern.

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

You can create an Auto Scaling group directly from an EC2 instance. When you use this feature, Auto Scaling automatically creates a launch configuration for you as well.

Explanation

Explanation

Auto Scaling can start and stop the instance at a pre-defined time. Here, the total running time is unknown. Thus, the user has to use the CloudWatch alarm, which monitors the CPU utilization. The user can create an alarm that is triggered when the average CPU utilization percentage has been lower than 10 percent for 24 hours, signaling that it is idle and no longer in use. When the utilization is below the threshold limit, it will terminate the instance as a part of the instance action.

Explanation

Security Groups are essentially stateful firewalls at the instance level. Security Groups are associated with instances at launch time, and restrict or allow traffic based on port, protocol, and source/destination.

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

To establish a baseline you should, at a minimum, monitor the following items:

• CPU Utilization
• Memory Utilization
• Network Utilization
• Disk Performance
• Disk Space.

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

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

In Amazon Route 53, you cannot create a hosted zone for a top-level domain (TLD).

Explanation

Amazon SNS and CloudWatch are integrated so you can collect, view, and analyze metrics for every active Amazon SNS notification. By configuring CloudWatch for Amazon SNS, you can gain better insight into the performance of your Amazon SNS topics, push notifications, and SMS deliveries.

Explanation

When an Amazon EBS-backed instance is stopped, you’re not charged for instance usage; however, you’re still charged for volume storage. Amazon charges a full instance hour for every transition from a stopped state to a running state, even if you transition the instance multiple times within a single hour. In this scenario, the charge was $42, which is three times more than $14. This suggests that you stopped and restarted that instance twice during that hour (the initial $14, plus 2 x $14 for each restart).

Although some instances now have per-second billing available, this new billing structure does not apply to Windows instances at this point.

Explanation

Cost Explorer, this is a useful and powerful tool within Billing and Cost Management. It allows you to view historical billing information in a graphical format giving you greater insight to your AWS spend. A valuable tool that can help to identify where you should be focusing your cost optimization efforts. It also can forecast your estimated spend up to two months ahead using existing data as a reference. If you can see that your estimated future bills are becoming too high, you have the time now to identify where you can make and initiate cost reduction mechanisms to help mitigate the risk.

Cost Explorer comes configured with three pre-defined views which are commonly used to analyze spending across your account:

1. Monthly Spend by Service view – this covers the current and previous two months and is grouped by AWS services
2. Monthly Spend by Linked Account View – this covers the current and previous two months and is grouped by linked accounts
3. Daily Spend view – this covers the daily spend over the previous sixty days

Explanation

A security group acts as a virtual firewall for your instance to control inbound and outbound traffic. When you launch an instance in a VPC, you can assign the instance to up to five security groups. Security groups act at the instance level, not the subnet level. Therefore, each instance in a subnet in your VPC could be assigned to a different set of security groups. If you don’t specify a particular group at launch time, the instance is automatically assigned to the default security group for the VPC. If an instance is running in an Amazon VPC you can change which security groups are associated with an instance while the instance is running.

Explanation

Amazon CloudWatch Alarms have three possible states: OK: The metric is within the defined threshold ALARM: The metric is outside of the defined threshold INSUFFICIENT_DATA: The alarm has just started, the metric is not available, or not enough data is available for the metric to determine the alarm state

Explanation

Many instances can poll a single queue, but to keep multiple instances from processing the same SQS message, your application must delete the SQS message after processing it. While SQS does not guarantee a message will be processed only once, the same message being processed many times is probably an indication that the message is not being deleted following processing.

Explanation

If an EBS volume is attached to a running EC2 instance, the user needs to detach the volume from the original instance and then attach it to a new running instance. The user doesn’t need to stop or terminate the original instance.

Explanation

If you are looking to use replication to increase database availability while protecting your latest database updates against unplanned outages, consider running your DB instance as a Multi-AZ deployment. When you create or modify your DB instance to run as a Multi-AZ deployment, Amazon RDS will automatically provision and manage a “standby” replica in a different Availability Zone (independent infrastructure in a physically separate location). In the event of planned database maintenance, DB instance failure, or an Availability Zone failure, Amazon RDS will automatically failover to the standby so that database operations can resume quickly without administrative intervention. Multi-AZ deployments utilize synchronous replication, making database writes concurrently on both the primary and standby so that the standby will be up-to-date in the event a failover occurs.

Explanation

IAM policies allow you to specify what actions your IAM users are allowed to perform against your EC2 Instances. However, when it comes to access control, security groups are what you need in order to define and control the way you want your instances to be accessed, and whether or not certain kind of communications are allowed or not.

Explanation

The pricing of SQS is as follows: You pay only for what you use, and there is no minimum fee. The cost of Amazon SQS is calculated per request, plus data transfer charges for data transferred out of Amazon SQS. The Amazon SQS Free Tier provides you with 1 million requests per month at no charge. Many small-scale applications are able to operate entirely within the limits of the Free Tier. However, data transfer charges might still apply.