Chapter 2 (1-50) Domain 2—Define Performant Architectures

When replicating data from a primary RDS instance to a secondary one, how much will you be charged, in relation to the standard data transfer charge? A. Your data will be transferred at the standard data transfer charge. B. Your data will be transferred at half of the standard data transfer charge. C. Your data will be transferred at half of the standard data transfer charge up to 1 GB of transfer per day and then additional data at the standard data transfer charge. D. There is no charge for primary-to-secondary data replication

1. D. There is no way to reason through this; it is a matter of memorization. There is no charge associated with data replication in this scenario.

Which of the following are true about a read replica setup? (Choose two.) A. Automated backups are taken from the read replicas rather than the primary instance. B. The database engine on all instances is active. C. Each read replica instance can upgrade its database engine separate from the primary instance. D. Replication is synchronous.

10. B, C. No backups are taken from any instance automatically, including the primary instance, so A is false. Since each read replica has its own database instance running, both B and C are valid. Replication is asynchronous rather than synchronous (so D is false)

Which of the following statements are false? (Choose two.) A. Both read replicas and Multi-AZ configurations ensure that you have database instances in multiple availability zones. B. Both read replicas and Multi-AZ configurations provide disaster recovery options for your primary instance. C. A single database can both have a read replica and be part of a Multi-AZ setup. D. A read replica can be promoted to be a stand-alone database instance.

11. A, B. A is false because you can create read replicas in the same AZ as the primary instance. There is no requirement to use multiple AZs, as there is with a Multi-AZ setup. B is also false; read replicas provide no disaster recovery options. Both C and D are true.

Which of the following statements is true? A. A Multi-AZ setup is aimed at fault tolerance, while a read replica setup is aimed at scalability. B. Both read replicas and Multi-AZ configurations are aimed at fault tolerance. C. A Multi-AZ setup is aimed at scalability, while a read replica setup is aimed at fault tolerance. D. Both read replicas and Multi-AZ configurations are aimed at scalability.

12. A. Only A is correct. A Multi-AZ setup is focused on disaster recovery and fault tolerance, while read replicas provide performance and scalability.

To how many EBS volumes can a single EC2 instance attach? A. 1 B. 2 C. 27 D. Unlimited

33. C. Officially, instances can have up to 28 attachments. One of those attachments is the network interface attachment, leaving 27 attachments available for EBS volumes. However, the better approach is to remember that an instance can attach to a root volume and several more volumes (more than two); this eliminates options A and B. Additionally, instances cannot have unlimited attachments. This leaves the correct answer, C.

How many EC2 instances can be attached to a single EBS volume at one time? A. 1 B. 2 C. 27 D. Unlimited

34. A. Be careful with the wording, to ensure that you do not misread this as asking how many EBS volumes can be attached to an EC2 instance (a different question altogether). A single EBS volume can only be attached to one instance at a time.

Which of the following protocols are supported by an application load balancer? (Choose two.) A. SSH B. HTTP C. HTTPS D. FTP

35. B, C. This should be an easy answer: Application load balancers, as well as classic load balancers, only support HTTP and HTTPS.

Which of the following provide ways to automate the backup of your RDS database? (Choose two.) A. Automated snapshots B. S3 lifecycle management policies C. Automated backups D. Data pipeline

36. A, C. RDS provides two (and only two) methods for backing up RDS databases at this point: automated backups and automated snapshots. S3 lifecycle management policies are not applicable to RDS databases, and data pipeline is not relevant in this context.

Which of the following storage classes has the lowest durability? A. S3 standard B. S3-IA C. Glacier D. They all have equal durability

45. D. This is a question where the answer is nonintuitive. All the S3 storage classes have the same durability. Even S3 One Zone-IA has 11 9s of durability in the single availability zone in which it resides.

Which of the following storage classes has the highest availability? A. S3 standard B. S3-IA C. Glacier D. They all have equal availability.

46. A. Availability starts at 99.99% for S3 and then decreases to 99.9% for S3-IA, 99.5% for S3 One Zone-IA, and finally N/A for Glacier.

Which of the following storage classes support automated lifecycle transitions? A. S3 standard B. S3-IA C. Glacier D. They all support lifecycle transitions.

47. D. This question is easy if you recall that lifecycle transitions are concerned with moving between these storage classes. Therefore, all of these classes support those transitions.

Where is data stored when placed into S3-IA? (Choose two.) A. In the region specified at bucket creation B. In a special AWS "global" region for S3 storage C. In at least three availability zones D. In a single availability zone within at least three regions

48. A, C. All S3 and S3-IA data is stored in a single region and within at least three availability zones within that region. There is no "global" region for S3 storage.

You need to perform a large amount of OLAP. Which AWS service would you choose? A. DynamoDB B. RDS Aurora C. Redshift D. Oracle installed on EC2 instances

49. C. Redshift is the only database or service in this list suitable for online analytics processing (OLAP). DynamoDB is an object database (NoSQL), and both Aurora and Oracle are relational databases, better suited for transaction processing.

Which of the following databases support read replicas? A. Oracle B. MySQL C. DynamoDB D. All of the above

5. B. Currently, read replicas in RDS are only supported by MariaDB, MySQL, and PostgreSQL.

What is the maximum allowable RDS volume size when using provisioned IOPS storage? A. 8 TB B. 16 TB C. 12 TB D. 1 PB

50. B. All the major databases supported by RDS—MariaDB, SQL Server, MySQL, Oracle, and PostgreSQL—allow up to 16 TB of storage for a provisioned IOPS volume.

Which of the following is true about a read replica? (Choose two.) A. It is a read-only instance of a primary database. B. It can only exist in the same region as the primary database, although it can be in a different availability zone. C. It is updated via asynchronous replication from the primary instance D. It is updated via synchronous replication from the primary instance.

6. A, C. A read replica is a read-only instance of a database created from a snapshot of the primary instance (A). Read replicas can be in the same instance, or a different one, as the primary instance (so B is false). Read replicas are updated via asynchronous replication—the most performant approach—from the primary database.

Which of the following is true about an RDS read replica configuration? (Choose two.) A. Only three read replicas can be set up for a single primary database instance. B. Only MariaDB, MySQL, and Aurora are supported. C. A read replica replicates all databases in the primary instance. D. A read replica can exist in a different region than the primary instance.

7. C, D. Read replicas can be in a different region than the primary instance (D), and they replicate all the databases in the primary instance (C). You can have up to five read replicas at a time for a single instance (so A is false). While MySQL and MariaDB are supported (B), Aurora is not.

How do applications communicate with read replica instances? A. Through the read replica REST API provided by RDS B. ELBs and ALBs will automatically translate requests to a read replica to use the read replica REST API provided by RDS. C. Each read replica provides a read replica key that allows applications to communicate with the instance as if it were a normal database instance. D. Applications communicate with a read replica exactly as they would with a non-read replica.

13. D. There is no difference in how applications communicate with read replicas as compared to the communication with non-replica instances. In fact, applications don't "know" that they're communicating with a read replica other than an inability to make writes.

Which of the following are valid reasons to use read replication? (Choose two.) A. You have a read-heavy database that is peaking in traffic. B. You have a large number of errors reported by applications trying to update user entries in your current database and want to reduce these errors. C. You want an automated disaster recovery solution in case you lose an AZ. D. You have a large number of business reporting queries that are currently interfering with customer application performance

14. A, D. A and D are both solutions that would be aided by additional read-only instances. B is not a valid answer because updating records would still only be possible with the primary instance; read replicas don't support writes. C is incorrect because read replicas do not provide automated fault recovery.

Does a read replica provide any assistance at all in creating a fault-tolerant database setup? A. Yes, it provides automated backups to the read replicas. B. Yes, if the primary instance fails, one of the replicas can be manually promoted to a stand-alone database instance. C. Yes, if the primary instance fails, one of the replicas will be automatically promoted to a stand-alone database instance. D. No

15. B. You need to be careful here. While read replicas are not advertised or even suggested as solutions for disaster recovery, option B does provide a somewhat manual process to use them in that manner. While you get no automated backups or failover (A or C), you can manually promote a read replica instance to a stand-alone instance if you have to. Still, a Multi-AZ setup is almost always a more robust solution for fault tolerance.

Which of the following are valid reasons to use read replication? (Choose two.) A. You have customers in a region geographically distant from your primary instance and want to improve their read performance when they access your applications hosted in regions closer to them. B. Your current database instance is showing memory saturation with current traffic loads. C. Your boss has asked for an automated backup solution that takes advantage of AWS managed services. D. You need to perform additional OLTP queries and want to improve the performance of those queries

16. A, B. Both A and B are ideal situations for read replicas. C is the usual incorrect answer: read replicas don't provide automated backups. And D is not accurate; the actual database processing doesn't improve; you are merely adding more sources for reading data for clients.

Can you configure a database instance to be both a read replica and a primary database instance for the original instance? A. Yes, as long as the instances are all in the same availability zone. B. Yes, if you turn on circular replication in both primary database instances. C. Yes, as long as the instances are not in the same availability zone. D. No, AWS does not support circular replication.

17. D. AWS does not support circular replication through RDS. While some of the databases supported by RDS do, RDS itself does not provide access to this functionality.

In which of the following ways can you create a read replica? (Choose two.) A. Through the AWS console B. Through the AWS online support system C. Through the AWS API D. Through Elastic Beanstalk

18. A, C. You can create a read replica through the AWS console (A), the AWS API (C), and the AWS CLI (not mentioned, but still true).

How are automated backups related to read replicas? A. They are not; read replicas and automated backups have no relationship at all. B. Read replicas do not create automatic backups, but the primary database instance must have automatic backups enabled to create read replicas. C. Read replicas cause the primary database instance to automatically begin backing up. D. Each read replica is automatically backed up after an initial read from the primary database instance.

19. B. As has been said numerous times, read replicas are not a backup strategy, nor do they cause automatic backups to be set up. However, you must turn on automatic backups for the primary database instance to enable read replicas.

Which of the following are valid options for where an RDS read replica is set up in relation to the primary instance? (Choose two.) A. In the same region as the primary instance B. In a separate region from the primary instance C. In an instance running on premises D. Both A and B

2. C, D. All of these are valid options. Although it's not particularly common, you can set up a read replica in an on-premises instance. Additionally, read replicas are often created in separate regions from the primary instance, to improve performance for clients closer to different regions than the primary instance.

Can a database instance be a read replica of one database and the source instance for another read replica? A. Yes, as long as the source and replicant database are not the same instance. B. No, a database cannot be both a read replica and a source database. C. Yes, as long as the source and replicant database are in the same availability zone. D. Yes, as long as you enable circular replication on both databases.

20. A. This bears careful reading. Amazon RDS does not support circular replication, which means one database reads from a second database but then is replicated back by that second database. However, it is absolutely permissible for one database to replicate another database and then be the source for a third database. This makes option A correct.

How quickly can you make changes to the backup window used by your RDS instance? A. Changes to the window via the console take place within 1 hour; changes made via the API take place immediately. B. Changes to the window take place after the next complete backup occurs. C. Changes to the window via the API take place within 1 hour; changes made via the console take place immediately. D. Changes to the window take place immediately

21. D. There is no difference in response to a change in the backup window based on how that window is changed (API, console, etc.). All changes take place immediately.

What is the longest backup retention window that Amazon RDS allows? A. 30 days B. 35 days C. 45 days D. 365 days

22. B. This is another straight memorization question: Amazon RDS backups can be retained for up to 35 days, and no longer.

You have an Oracle installation using a custom geospatial plug-in. You also want to ensure the maximum throughput for database operations once those operations are begun by the plug-in. How would you set up Oracle to meet these requirements? A. Set up Oracle using RDS with provisioned IOPS. B. Set up Oracle using RDS with magnetic storage. C. Install Oracle on an EC2 instance with a provisioned IOPS EBS volume. D. Install Oracle on an EC2 instance with a magnetic EBS volume.

23. C. There are two components to this question: using RDS or EC2 for Oracle hosting and the class of storage to select. While RDS is a better option in the general case, it is likely not possible to use RDS in this scenario due to the custom plug-in required. This eliminates A and B. Given an installation on EC2, then, the question becomes which storage class is faster: provisioned IOPS or magnetic. The answer here is always provisioned IOPS.

In what scenarios would you install an Oracle database on an EC2 instance rather than using RDS? (Choose two.) A. You want to use an ALB to support multiple instances and round-robin request distributions. B. Your database size is greater than 80% of the maximum database size in RDS. C. You have custom plug-ins that will not run in RDS. D. You want to ensure that your database is only accessible through your private subnet in a VPC.

24. B, C. Option C should be the immediately obvious first choice. Anytime you have custom plug-ins, you will likely need to install your database on an EC2 instance rather than using RDS. Options A and D are really both about network routes and services around your database, and both can be accomplished without affecting your EC2 vs. RDS decision. This leaves B, which also logically makes sense: If you have a very large database, and it will grow (as almost all databases do), then sizing restraints on RDS can be a limiting factor.

Which of the following are SQL-based options in RDS? (Choose two.) A. Aurora B. DynamoDB C. MariaDB D. Redshift

25. A, C. This should be an easy question if you're prepared. While it's easy to forget if Aurora and MariaDB are RDS options—they are!—you should know that DynamoDB is AWS's NoSQL database, and Redshift is a data-warehousing solution.

You are a new architect at a company building out a large-scale database deployment for web applications that receive thousands of requests per minute. The previous architect suggested a Multi-AZ deployment in RDS to ensure maximum responsiveness to the web tier. Is this a good approach for high performance? A. No, because a Multi-AZ deployment is no faster in responding to requests than a standard RDS deployment. B. Yes, because the additional databases in a Multi-AZ deployment will share the request load from the web tier. C. Yes, because a Multi-AZ deployment will ensure that if the primary database goes down, a secondary database will be current and available. D. No, because a Multi-AZ deployment can only field requests from the availability zone in which each database resides.

26. A. This is not particularly difficult as long as you understand that a Multi-AZ deployment is concerned with failover, not performance. Option A is correct: There is no particular performance increase in a Multi-AZ deployment, unless read replicas are also turned on (which isn't specified). B is false because only the primary database responds to requests in a Multi-AZ deployment. C is actually a true statement but does not have a bearing on the subject of the question: performance. And D doesn't actually make sense in the context of the question at all!

You launch an EC2 instance that has two volumes attached: a root and an additional volume, both created with default settings. What happens to each volume when you terminate the instance? A. The root volume is deleted and the additional volume is preserved. B. Both volumes are deleted. C. Both volumes are preserved. D. The instance is unable to terminate until the root volume is deleted.

27. A. This one is a little tricky as it requires understanding what default options AWS puts in place. By default, root volumes are terminated on instance deletion, and by default, additional EBS volumes attached to an instance are not. This makes option A true. However, note that these settings can be changed! Also note that option D is not true in any configuration.

How many S3 buckets can you add to an account? A. 100 B. 100 by default, but this can be increased by contacting AWS. C. It depends on the default set for the new account by AWS. D. It depends on how the account is configured at account creation.

28. B. The default for all new accounts is 100 allowed S3 buckets; this is consistent across AWS and does not change via configuration (meaning that C and D are not correct). However, this value can be raised through asking AWS for an exception and providing a reasonable justification, making B the correct answer.

What type of replication occurs in a Multi-AZ RDS setup? A. Sequential replication B. Synchronous replication C. Asynchronous replication D. Synchronous replication for full backups and asynchronous replication for incremental backups.

29. B. Replication occurs synchronously from a primary instance to a secondary instance in a Multi-AZ setup. Asynchronous replication only occurs in a read replica setup (which can be enabled in addition to a Multi-AZ setup).

What is the primary purpose of a read replica RDS configuration? A. Disaster recovery B. Fault tolerance C. Performance D. Security

3. C. A read replica configuration is aimed squarely at increasing database performance, specifically the performance of reading data from an RDS instance.

What type of replication occurs in a read replica RDS setup? A. Sequential replication B. Synchronous replication C. Asynchronous replication D. Synchronous replication for full backups and asynchronous replication for incremental backups.

30. C. Replication occurs asynchronously from a primary instance to the various read replicas in a read replica setup. As a result, updates are not guaranteed to be instant on the read replicas. Synchronous replication occurs in a Multi-AZ setup.

Which of the following protocols and routing approaches does a classic load balancer support? (Choose two.) A. IPv4 B. IPv6 C. HTTP/2 D. Registering targets in target groups and routing traffic to those groups

31. A, B. Classic load balancers support both IPv4 and IPv6. They support HTTP/1 and HTTP/1.1, but only application load balancers support HTTP/2. Further, you must register individual instances, rather than target groups, with classic load balancers; registering target groups is a functionality only available with application load balancers.

How many elastic IP addresses can you create per region by default in a new AWS account? A. 5 B. 10 C. 20 D. There is no preset limit.

32. A. AWS accounts allow you five elastic IP addresses per region by default. As with most AWS defaults, this can be raised by contacting AWS and providing a reasonable justification.

You have an EC2 instance running a heavy compute process that is constantly writing data to and from a cache on disk. How and when should you take a snapshot of the instance to ensure the most complete snapshot? A. Take a snapshot of the instance from the AWS console. B. Shut down the instance and take a snapshot of the instance. C. Take a snapshot of the instance from the AWS CLI. D. Detach the EBS volume attached to the instance and take a snapshot of both the EC2 and EBS instance.

37. B. Data written to and from cache is ephemeral, and if your instance is reading and writing that data frequently, the only way to ensure that your snapshot isn't missing data is to stop the instance from running altogether and to then take a snapshot (B). Both A and C will take snapshots but will likely miss any cached data. With option D, you cannot detach a root volume from an instance (it's unclear from the question if the cached data is being written to EBS, EFS, or another storage mechanism in any case), and so it is not a safe choice.

Your web-based application uses a large RDS data store to write and read user profile information. The latest marketing campaign has increased traffic to the application by an order of magnitude. Users are reporting long delays when logging in after having signed up. Which solutions are valid approaches to addressing this lag? (Choose two.) A. Set up a Multi-AZ configuration for your RDS and round-robin requests between the two RDS instances to spread out traffic. B. Employ ElastiCache to cache users' credentials after their initial visit to reduce trips to the database from the web application. C. Set up a read replica configuration for your RDS and round-robin requests between all the replicas to spread out traffic. D. Increase the number of EC2 instances allocated to your Auto Scaling group to spread out traffic on the web application tier.

38. B, C. Option A is invalid because Multi-AZ is a disaster recovery solution; the primary database is the only instance that can respond to traffic in normal operation (unless read replicas are also set up). Option B is valid; caching user data would reduce round trips to the database and should reduce lag for users. Option C also makes sense, as having additional databases from which to read should decrease network latency to a single RDS instance. Option D is not helpful as the problem appears to be in retrieving credentials, not in the web tier itself.

Your users are now storing all of their photos in your cloud-based application. CloudWatch metrics suggests that photos are written an average of 5 times per user per day and read 100 times per user per day. If photos are lost, user surveys indicate that users are not typically upset and simply re-upload the missing photo or ignore the missing photo altogether. What is the most cost-effective recommendation for the S3 storage class to use? A. Standard S3 B. S3-IA C. S3 One Zone-IA D. S3 RRS

39. C. Standard S3 (A) is not a bad choice, but is the most expensive, and both it and S3-IA (B) are more expensive than S3 One Zone-IA because of their increased availability and resilience. The key here is that photos can be lost without an issue, making S3 One Zone-IA the better option. S3 RRS is no longer recommended by AWS.

Which of the following databases support read replicas? A. MariaDB B. MySQL C. PostgreSQL D. All of the above

4. D. All three of these databases support read replicas. Most other databases supported by RDS (Oracle, for example, or Aurora) offer other approaches to gain similar functionality to read replicas but do not support the AWS read replica functionality.

You are consulting for a company that wants to migrate its 85TB data store into S3. It is willing to upload the data into S3 every night in small batches but is concerned that overseas customers using its other applications might experience network latency as they are transferring files into S3. What solution should you recommend to move the company's data? A. Enable Transfer Acceleration on S3. B. Direct Connect C. Snowball D. Set up a VPN that uses a virtual private gateway for transferring the data.

40. C. This should be automatic: Anytime a large data transfer is involved (especially on an AWS exam!), the answer should be Snowball. This comes up a lot and should be an easy correct answer.

Which of the following are valid reasons for using Multipart Upload for uploading objects to S3? (Choose two.) A. You need a solution that recovers from network issues. B. You need a solution to upload files larger than 10 GB. C. You need a solution for increasing the security around uploaded objects. D. You need a solution to decrease the time required to upload large files.

41. A, D. The only tricky answer here is B. While Multipart Upload absolutely would improve the experience of uploading large files (larger than 10 GB, for example), it is not required; therefore, option B is not the best option to choose. Options A and D both are only possible with Multipart Upload enabled. Option C is false, as security is not related to Multipart Upload.

In which of the following situations would you recommend using a placement group? A. Your fleet of EC2 instances requires high disk IO. B. Your fleet of EC2 instances requires high network throughput across two availability zones. C. Your fleet of EC2 instances requires high network throughput within a single availability zone. D. Your fleet of EC2 instances requires high network throughput to S3 buckets.

42. C. A placement group is concerned primarily with network throughput and reducing latency among EC2 instances within a single availability zone. AWS does support a placement group spanning multiple AZs via spread placement groups, but unless "spread" is specifically mentioned, you should assume the question references a "normal" (or "cluster") placement group.

Which of the following statements are true about cluster placement groups? (Choose two.) A. All instances in the group must be in the same availability zone. B. Instances in the group will see lowered network latency in communicating with each other. C. Instances in the group will see improved disk write performance when communicating with S3. D. Instances in the group must all be of the same instance class.

43. A, B. Cluster placement groups (the default type of placement group) must be made up of instances that exist within a single availability zone(A). This results in increased throughput for network activity (B) but does not affect actual disk performance when writing to S3 (C). Instances can also be of different types, so D is also false

Which of the following statements are true about spread placement groups? (Choose two.) A. All instances in the group must be in the same availability zone. B. Instances in the group will see lowered network latency in communicating with each other. C. You can have up to seven instances in multiple availability zones in the group. D. AWS provisions the hardware rather than having you specify the distinct hardware for the group.

44. B, C. Spread placement groups can span availability zones and support up to seven instances per zone (C). Like cluster groups, this results in increased throughput for network activity (B). You must specify the distinct underlying hardware for spread placement groups, which means that D is false.

You have a primary database set up to use read replicas running on an instance in US East 1. You have three read replicas also in US East 1 and two additional replicas in US West 2. You are trying to create a new replica in EU West 1 and are getting an error. What do you need to do to resolve this error and successfully create a new read replica in EU West 1? A. Turn on the Multi-AZ option for your primary instance. B. You can't create the replica in EU West 1. Instead, create the replica in another US region to avoid regulations about read replicas in the EU. C. Contact AWS about raising the number of read replicas allowed from 5 to 8. D. Turn off one of the read replicas in US East 1 and then you can create the instance in EU West 1

8. D. The root issue here is that a read replica setup only allows for five read replicas. This is not a limit that can be raised by AWS either (so C is out). Option A won't address the issue, and option B isn't accurate; there are no EU limitations affecting the issue here. The only answer that would result in being able to create the instance is D: By turning off an existing instance, you can create a new fifth replica in the desired region.

Which of the following are true about a read replica setup? (Choose two.) A. Backups are configured by default when you set up read replicas. B. They provide a highly scalable solution for your on-premises databases. C. They can exist within a single AZ, cross-AZ, or cross-region. D. A read replica can be promoted to a stand-alone database instance

9. C, D. Read replicas are focused on performance, so you can generally eliminate any answers related to disaster recovery—in this case, A. Read replicas work with RDS databases, as well, so B is out; on-premises databases aren't supported. This leaves C and D, which are both valid.