Monitoring & Troubleshooting
You are designing an online medical appointment system that allows patients to book an appointment with their preferred doctor at medical centers all over the country. The DynamoDB Streams feature is enabled in your DynamoDB database, which allows you to capture information about every modification to data items in your table. A Lambda function integrated with CloudWatch Events is used to process the data stream every 36 hours then store the results in an S3 bucket. However, you noticed that there are a lot of updated data in DynamoDB which are not sent to your S3 bucket even though there are no errors in the logs. Which of the following is the MOST appropriate solution for this issue?
Decrease the interval of running your function to 24 hours
A Docker application hosted on an ECS cluster has been encountering intermittent unavailability issues and time outs. The lead DevOps engineer instructed you to instrument the application to detect where high latencies are occurring and to determine the specific services and paths impacting application performance. Which of the following steps should you do to properly accomplish this task?
- Configure the port mappings and network mode settings in your task definition file to allow traffic on UDP port 2000. - Create a Docker image that runs the X-Ray daemon, upload it to a Docker image repository, and then deploy it to your Amazon ECS cluster.
A developer is instrumenting an application which will be hosted in a large On-Demand EC2 instance in AWS. Which of the following are valid considerations in X-Ray that the developer should follow?
- Set the namespace subsegment field to aws for AWS SDK calls and remote for other downstream calls - Set the metadata object with any additional custom data that you want to store in the segment
You were recently hired as a developer for a leading insurance firm in Asia which has a hybrid cloud architecture with AWS. The project that was assigned to you involves setting up a static website using Amazon S3 with a CORS configuration as shown below: <?xml version="1.0" encoding="UTF-8"?> <CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/"> <CORSRule> <AllowedOrigin>https://tutorialsdojo.com</AllowedOrigin> <AllowedMethod>GET</AllowedMethod> <AllowedMethod>PUT</AllowedMethod> <AllowedMethod>POST</AllowedMethod> <AllowedMethod>DELETE</AllowedMethod> <AllowedHeader>*</AllowedHeader> <ExposeHeader>ETag</ExposeHeader> <ExposeHeader>x-amz-meta-custom-header</ExposeHeader> <MaxAgeSeconds>3600</MaxAgeSeconds> </CORSRule> </CORSConfiguration> Which of the following statements are TRUE with regards to this S3 configuration?
- This will cause the browser to cache the response of the preflight OPTIONS request for 1 hour. - It allows a user to view, add, remove or update objects inside the S3 bucket from the domain tutorialsdojo.com.
An application is hosted in an Auto Scaling group of EC2 instances behind an Application Load Balancer. You want to automatically monitor the CPU Utilization of each and every instances of your application stack throughout the day using Amazon CloudWatch. In this scenario, what is the time period of data that CloudWatch receives and aggregates from EC2 by default?
5 minutes
An application hosted in an ECS Cluster has been instrumented to use AWS X-Ray. It is configured with a reservoir size of 50 and a fixed rate of 10% to sample 100 incoming requests per second. With this configuration, how many total sampled requests per second will there be?
55
A leading financial company has recently deployed their application to AWS using Lambda and API Gateway. However, they noticed that all metrics are being populated in their CloudWatch dashboard except for CacheHitCount and CacheMissCount. What could be the MOST likely cause of this issue?
API Caching is not enabled in API Gateway.
A serverless application, which is composed of Lambda functions integrated with API Gateway and DynamoDB, processes ad hoc requests that are sent by its users. Due to the recent spike in incoming traffic, some of your customers are complaining that they are getting HTTP 504 errors from time to time. Which of the following is the MOST likely cause of this issue?
API Gateway request has timed out because the underlying Lambda function has been running for more than 29 seconds.
A leading insurance firm is hosting its customer portal in Elastic Beanstalk which has an RDS database in AWS. The support team in your company discovered a lot of SQL injection attempts and cross-site scripting attacks to the portal, which is starting to affect the production environment. Which of the following services should you implement to mitigate this attack?
AWS WAF
An application uses a RESTful API hosted in AWS, which uses Amazon API Gateway, AWS Lambda, and DynamoDB. There has been a production issue in your application and you want to trace and analyze the user requests as they go through your Amazon API Gateway API's and eventually to the underlying services. Which of these options is the MOST appropriate service that you should use to troubleshoot this issue?
AWS X-Ray
A newly hired developer has been instructed to debug an application. She tried to access the X-Ray console to view service maps and segments but her current access is insufficient. Which of the following is the MOST appropriate managed policy that should be granted to the developer?
AWSXrayReadOnlyAccess
A developer is planning to use the AWS Elastic Beanstalk console to run the AWS X-Ray daemon on the EC2 instances in her application environment. She will use X-Ray to construct a service map to help identify issues with her application and to provide insight on which application component to optimize. The environment is using a default Elastic Beanstalk instance profile. Which IAM managed policy does Elastic Beanstalk use for the X-Ray daemon to upload data to X-Ray?
AWSXrayWriteOnlyAccess
A Software Engineer is refactoring a Lambda function, which currently uses a public GraphQL API from the Internet as part of its processing. The new requirement states that the function should process the data and store the results to a database hosted in your VPC. The additional VPC-specific information has already been configured in the function and the database connection has been successfully established. However, after testing, he found that the function can't connect to the Internet anymore. Which of the following should the Software Engineer do to fix this issue?
Add a NAT gateway to your VPC, and ensure that the associated security group of the Lambda function allows outbound connections.
A web application hosted in Elastic Beanstalk has a configuration file named .ebextensions/debugging.config which has the following content: option_settings: aws:elasticbeanstalk:xray: XRayEnabled: true For its database tier, it uses RDS with Multi-AZ deployments configuration and Read Replicas. There is a new requirement to record calls that your application makes to RDS and other internal or external HTTP web APIs. The tracing information should also include the actual SQL database queries sent by the application, which can be searched using the filter expressions in the X-Ray Console. Which of the following should you do to satisfy the above task?
Add annotations in the subsegment section of the segment document.
An application, which already uses X-Ray, generates thousands of trace data every hour. The developer wants to use a filter expression which will limit the results based on custom attributes or keys that he specifies. How should the developer refactor the application in order to filter the results in the X-Ray console?
Add the custom attributes as annotations in your segment document.
A Lambda-based application consists of several functions. Once triggered, these functions will call various downstream resources such as a DynamoDB table or an S3 bucket, or make other API calls. There is a requirement to allow the developers to trace the event source that invoked your Lambda functions and trace the downstream calls that your functions made. The number of requests and the execution duration per request should also be monitored. Which of the following services should you use to achieve this?
Amazon CloudWatch and AWS X-Ray
A serverless application that you are managing is using API Gateway with a Lambda proxy integration. You enabled API caching in API Gateway to improve the read performance of the application. For system monitoring, you need to track the number of requests served from the backend in a given period. Which of the following metrics in CloudWatch should you use in this scenario?
CacheMissCount
You are working as a software developer for a technology company which has an application hosted in a Reserved EC2 instance. The application uses Amazon SDK to communicate to other AWS services such as DynamoDB, S3, Kinesis, and many others. You need to ensure that all of the API calls to your AWS resources are logged and stored to comply with the IT audit. Which of the following is the MOST suitable service that you should use to meet this requirement?
CloudTrail
A financial company has a cryptocurrency application which is hosted in Elastic Beanstalk in AWS for a couple of months. Recently, the application's performance is degrading so you decide to check the CPU and memory utilization of the underlying EC2 instances in CloudWatch. You can see the CPU utilization of the instances but not the memory utilization. Which of the following is the MOST likely cause of this issue?
CloudWatch does not track memory utilization by default
An online stock trading platform is hosted in an Auto Scaling group of EC2 instances with an Application Load Balancer in front to evenly distribute the incoming traffic. The developer must capture information about the IP traffic going to and from network interfaces in your VPC to comply with financial regulatory requirements. Which of the following options should the developer do to meet the requirement?
Create a flow log in your VPC
You have an Auto Scaling group of on-demand EC2 instances behind a Classic Load Balancer. Even if the scale-up threshold hasn't been met, your manager requested you to manually increase the current number of instances to 20 to prepare for a temporary influx of requests. Which of the following options will you modify to manually place 20 running instances in your Auto Scaling group?
Desired capacity
A new IT policy requires you to trace all calls that your Node.js application sends to external HTTP web APIs as well as SQL database queries. You have to instrument your application, which is hosted in Elastic Beanstalk, in order to properly trace the calls via the X-Ray console. What should you do to comply with the given requirement?
Enable the X-Ray daemon by including the xray-daemon.config configuration file in the .ebextensions directory of your source code.
A leading commercial bank has an online banking portal which is hosted in an Auto Scaling group of EC2 instances with an Application Load Balancer in front to distribute the incoming traffic. The application has been instrumented and the X-Ray daemon has been installed to all instances to allow debugging and troubleshooting using AWS X-Ray. In this architecture, from which source will AWS X-Ray fetch the client IP address?
From the X-Forwarded-For header of the request
A company is using a combination of CodeCommit, CodeBuild, CodePipeline and CodeDeploy services for its continuous integration and continuous delivery (CI/CD) pipeline on AWS. They want someone to perform a code review before a revision is allowed into the next stage of a pipeline. If the action is approved, the pipeline execution resumes but if it is not then the pipeline execution will not proceed. Which of the following is the MOST suitable solution to implement in this scenario?
Implement a manual approval actions configuration in CodePipeline using an SNS Topic.
An application is hosted in an On-Demand Linux EC2 instance which uses an RDS database. There has been a lot of complaints that the application often crashes but the support team can't pinpoint the problem using CloudWatch. To properly troubleshoot the issue, the team needs to track the memory and swap usage of the instance. Which of the following is the MOST suitable solution to use in this scenario?
Install the CloudWatch custom monitoring scripts
An API gateway with a Lambda proxy integration takes a long time to complete its processing. There were also occurrences where some requests timed out. You want to monitor the responsiveness of your API calls as well as the underlying Lambda function. Which of the following CloudWatch metrics should you use to troubleshoot this issue?
Latency & IntegrationLatency
A mission-critical application is required to have a monitoring system which can provide immediate insight into its sub-minute activity. You are required to collect the data of all of the users who are currently logged in to the system every 10 seconds. Which of the following options is the MOST suitable solution that you should do to meet the above requirements?
Publish a high-resolution custom metric to CloudWatch.
A financial company has a forex trading portal that is written in MERN stack and has been running on Elastic Beanstalk in AWS. The portal processes 200 requests per second and the results are stored in a DynamoDB database. For troubleshooting purposes, you were assigned to enable AWS X-Ray and sample a total of 160 requests per second. You should also ensure that you sample a percentage of matching requests after the reservoir is exhausted. How should you configure the sampling rules in X-Ray to meet the above requirement?
Set the reservoir size to 150 and the fixed rate to 20%
A developer recently deployed a serverless application, which consists of a Lambda function, API Gateway and DynamoDB using the sam deploy CLI command. The Lambda function is invoked through the API Gateway then processes and stores the data to a DynamoDB table with an average time of 20 minutes. However, the IT Support team noticed that there are several terminated Lambda invocations that happen every day which is causing data discrepancy. Which of the following options is the MOST likely root cause of this problem?
The failed Lambda invocations have been running for over 15 minutes and reached the maximum execution time.
A serverless application, which uses a Lambda function integrated with API Gateway, provides data to a front-end application written in ReactJS. The users are complaining that they are getting HTTP 504 errors intermittently when they are using the application in peak times. Which of the following is the MOST likely cause of this issue?
The underlying Lambda function has been running for more than 29 seconds causing the API Gateway request to time out.
A developer configured an Amazon API Gateway proxy integration named MyAPI to work with a Lambda function. However, when the API is being called, the developer receives a 502 Bad Gateway error. She tried invoking the underlying function but it properly returns the result in XML format. What is the MOST likely root cause of this issue?
There is an incompatible output returned from a Lambda proxy integration backend.
A company has an application hosted in an ECS Cluster which is heavily using an RDS database. A developer needs to closely monitor how the different processes on a DB instance use the CPU such as the percentage of the CPU bandwidth or the total memory consumed by each process to ensure application performance. Which of the following is the MOST suitable solution that the developer should implement?
Use Enhanced Monitoring in RDS
A developer is using AWS X-Ray to create a visualization scheme to monitor the requests that goes through their serverless application. There are different services that communicate with the application and all these requests should be traced in X-Ray, including all the downstream calls made by the application to AWS resources. Which of the following actions should the developer implement for this scenario?
Use X-Ray SDK to generate segment documents with subsegments and send them to the X-Ray daemon, which will buffer them and upload to the X-Ray API in batches.
n the next financial year, your company decided to develop a totally new version of their legacy application which will be using Node.js and GraphQL. The new architecture should provide them an end-to-end view of requests as they travel through their application, and shows a map of the application's underlying components. The application will be hosted in an Auto Scaling group of Linux EC2 instances and it must be instrumented so it can send the trace data to the AWS X-Ray service. Which of the following options is the MOST suitable way to satisfy this requirement?
Use a user data script to install the X-Ray daemon.
A developer uses AWS X-Ray to create a trace on an instrumented web application and gain insights on how to better optimize its performance. The segment documents being sent by the application contain annotations which the developer wants to utilize in order to identify and filter out specific data from the trace. Which of the following should the developer do in order to satisfy this requirement with minimal configuration?
Use filter expressions via the X-Ray console and fetch the trace IDs and annotations using the GetTraceSummaries API
A developer has instrumented an application using the X-Ray SDK to collect all data about the requests that an application serves. There is a new requirement to develop a custom debug tool which will enable them to view the full traces of their application without using the X-Ray console. What should the developer do to accomplish this task?
Use the GetTraceSummaries API to get the list of trace IDs of the application and then retrieve the list of traces using BatchGetTraces API
A recently deployed Lambda function has an intermittent issue in processing customer data. You enabled the active tracing option in order to detect, analyze, and optimize performance issues of your function using the X-Ray service. Which of the following environment variables are used by AWS Lambda to facilitate communication with X-Ray?
_X_AMZN_TRACE_ID & AWS_XRAY_CONTEXT_MISSING