Module 10: Monitoring, elasticity and high availability Flashcards

1
Q

What is Amazon CloudWatch?

A

A monitoring and observability service that collects data from AWS resources, applications, and services in real-time.

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2
Q

What are the primary components of CloudWatch?

A

Metrics, Alarms, Logs, Events, and Dashboards.

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3
Q

What is a CloudWatch metric?

A

A data point representing a specific performance characteristic of a resource, such as CPU utilization or network traffic.

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4
Q

How often are metrics collected by default for EC2 instances?

A

Every 5 minutes for basic monitoring, every 1 minute for detailed monitoring.

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5
Q

: How can you analyze log data in CloudWatch?

A

Use CloudWatch Logs Insights to query and analyze log data interactively.

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6
Q

What is a CloudWatch Alarm?

A

A feature that monitors a specific metric and performs an action (e.g., sending notifications) when the metric crosses a defined threshold.

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7
Q

What are the three alarm states in CloudWatch?

A

OK, ALARM, and INSUFFICIENT_DATA.

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8
Q

What action can a CloudWatch Alarm trigger?

A

Send notifications via SNS, perform an EC2 Auto Scaling action, or execute an AWS Lambda function for example.

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9
Q

What is a CloudWatch Dashboard?

A

A customizable, visual interface for monitoring metrics and alarms across multiple AWS resources.

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10
Q

How can you share a CloudWatch Dashboard?

A

Dashboards can be shared with team members or made public for specific viewers.

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11
Q

What is Amazon EventBridge?

A

A serverless event bus service that makes it easy to connect applications using event-driven architecture.

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12
Q

What is an EventBridge Event Bus?

A

A logical grouping of events that applications can subscribe to and process. AWS services send events to the default event bus.

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13
Q

What is AWS Cost Explorer used for?

A

To visualize and analyze AWS costs and usage over time, identifying spending patterns and anomalies.

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14
Q

What is the AWS Budget tool used for?

A

To set custom cost, usage, or savings plans thresholds and receive alerts when those thresholds are breached.

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15
Q

What is AWS Cost and Usage Report for?

A

contains the most comprehensive set of AWS cost and usage data available, including additional metadata about AWS services, pricing, and reservations.AWS

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16
Q

What is vertical scaling?

A

Replacing a resource with a larger or smaller one (e.g., upgrading an EC2 instance for more RAM or CPU). It may involve downtime.

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17
Q

What is horizontal scaling?

A

Adding or removing instances or resources (e.g., increasing the number of EC2 instances). This enables building internet-scale applications.

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18
Q

Why is horizontal scaling preferred for high availability?

A

It distributes traffic across multiple instances, reducing the impact of failures and improving cost efficiency.

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19
Q

What is an Amazon EC2 Auto Scaling group?

A

A logical collection of EC2 instances managed across multiple Availability Zones.

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20
Q

What does a launch template specify in an Auto Scaling group?

A

Configuration details for EC2 instances, including AMI ID, instance type, and network settings.

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21
Q

What triggers Amazon EC2 Auto Scaling?

A

Scaling policies, schedule actions, and health checks from ELB or Auto Scaling.

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22
Q

What is the role of Elastic Load Balancing (ELB) in Auto Scaling?

A

ELB distributes incoming traffic to instances in the Auto Scaling group and reports unhealthy instances.

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23
Q

What are the benefits of EC2 Auto Scaling?

A

Better fault tolerance: Replaces unhealthy instances.
Better availability: Matches traffic demand dynamically.
Better cost management: Avoids overprovisioning.

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24
Q

What are the three capacity settings of an Auto Scaling group?
A:

A

Minimum capacity: Smallest number of instances needed.
Maximum capacity: Largest number of instances permitted.
Desired capacity: Optimal number of instances under normal conditions.

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25
Q

What is the significance of scaling in multiple Availability Zones?

A

Ensures high availability by distributing instances across zones, reducing the impact of a zone failure.

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26
Q

How does EC2 Auto Scaling handle Spot Instances?

A

It provisions Spot Instances if they are available, based on cost preferences in the launch template.

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27
Q

What are the types of scaling mechanisms for EC2 Auto Scaling?

A

Manual scaling: User adjusts capacity manually.
Scheduled scaling: Based on predefined times.
Dynamic scaling: Responds to real-time metrics.
Predictive scaling: Uses historical data for capacity forecasts.

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28
Q

What is target tracking scaling?

A

Adjusting capacity to maintain a specific metric (e.g., keeping CPU utilization at 50%).

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29
Q

How does step scaling differ from simple scaling?

A

Step scaling adjusts capacity based on the size of the alarm breach, while simple scaling waits for scaling to finish before responding to new alarms.

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30
Q

What is predictive scaling?

A

Uses machine learning to forecast traffic patterns and scale resources in advance.

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31
Q

What workloads are ideal for predictive scaling?

A

Cyclical traffic, batch processing, or applications with long initialization times.

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32
Q

Can dynamic and predictive scaling work together?

A

Yes, combining them ensures both proactive and reactive scaling for optimal efficiency.

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33
Q

What is an example of a target tracking policy?

A

Keeping average CPU utilization at 50%, scaling out when the metric exceeds the target and scaling in when it drops below.

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34
Q

What is a step adjustment in step scaling?

A

Defines how much capacity to add or remove based on the metric’s deviation from thresholds.

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35
Q

What is a scheduled scaling policy?

A

Automates scaling actions based on a specific date and time (e.g., scaling up every Wednesday morning).

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36
Q

Why is scaling out important during traffic spikes?

A

Prevents performance degradation by provisioning additional resources to meet demand.

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37
Q

What happens if a load balancer reports an unhealthy instance?

A

EC2 Auto Scaling terminates the unhealthy instance and replaces it with a new one.

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38
Q

How does an Auto Scaling group handle minimum capacity?

A

Ensures at least the minimum number of instances are running, even during low demand periods.

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39
Q

What metric does an Auto Scaling group commonly track for scaling?

A

CPU utilization, but it can track other metrics like SQS queue length or network traffic.

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40
Q

What is AWS Auto Scaling?

A

A service to configure scaling plans across multiple AWS services, such as Aurora, ECS, and DynamoDB.

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41
Q

What is Application Auto Scaling?

A

A service for scaling individual AWS resources like Lambda functions, SageMaker, or ElastiCache

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42
Q

How does Application Auto Scaling support target tracking?

A

Automatically adjusts resources to maintain a predefined target metric.

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43
Q

What is the main difference between AWS Auto Scaling and Application Auto Scaling?

A

AWS Auto Scaling manages scaling for groups of resources, while Application Auto Scaling focuses on individual scalable resources.

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44
Q

What are the two primary types of scaling for databases?

A

Vertical scaling (increasing instance size) and horizontal scaling (adding resources, such as read replicas).

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45
Q

What does “service-managed storage scaling” mean?

A

AWS automatically manages storage growth for databases like Aurora and DynamoDB.

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46
Q

Why is database scaling not instantaneous?

A

Scaling typically involves background processes that can take time to complete.

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47
Q

How can Aurora be scaled vertically?

A

By changing the DB instance class size.

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48
Q

How can Aurora be scaled horizontally?

A

By adding up to 15 read replicas.

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49
Q

What is Aurora Auto Scaling?

A

A feature that dynamically adjusts the number of Aurora Replicas based on workloads using CloudWatch metrics.

50
Q

How does Aurora Serverless handle scaling?

A

It uses Aurora Capacity Units (ACUs) to scale horizontally within a defined minimum and maximum range.

51
Q

What is an ACU in Aurora Serverless?

A

A unit of approximately 2 GiB of memory, corresponding CPU, and networking.

52
Q

Can Aurora Serverless handle intermittent workloads?

A

Yes, it automatically starts, stops, and scales based on demand.

53
Q

What are the two ways Aurora manages high availability during scaling?

A

Using replicas for failover and performing maintenance during scheduled windows.

54
Q

How is vertical scaling achieved in Amazon RDS?

A

By modifying the instance class or increasing storage size.

55
Q

What is the role of Multi-AZ in scaling Amazon RDS?

A

Minimizes downtime by upgrading the standby database first, then failing over to it.

56
Q

How does horizontal scaling work in Amazon RDS?

A

By adding read replicas to handle read-heavy workloads.

57
Q

Can RDS read replicas act as a primary database?

A

No, read replicas cannot replace the high availability features of Multi-AZ deployments.

58
Q

What is Amazon RDS storage auto scaling?

A

A feature that dynamically adjusts storage capacity based on workload requirements.

59
Q

What are the two capacity modes for DynamoDB tables?

A

On-demand mode and provisioned mode.

60
Q

What is the benefit of DynamoDB on-demand mode?

A

Automatically scales to accommodate spiky or unpredictable workloads.

61
Q

How does DynamoDB handle scaling in provisioned mode?

A

Uses Application Auto Scaling to adjust RCUs (Read Capacity Units) and WCUs (Write Capacity Units).

62
Q

What are global secondary indexes in DynamoDB?

A

Separate indexes that can be scaled independently to reduce load on the base table.

63
Q

Does DynamoDB automatically scale storage?

A

Yes, storage scaling is managed by the service.

64
Q

How does vertical scaling differ between Aurora and RDS?

A

Aurora scales by changing the instance class size, while RDS scales instance size and storage separately.

65
Q

How does horizontal scaling work for DynamoDB?

A

DynamoDB uses auto scaling for RCUs and WCUs, and supports scaling for global secondary indexes.

66
Q

What storage scaling features are unique to Aurora?

A

Storage scaling is service-managed and spans across Availability Zones as part of the cluster volume.

67
Q

What feature allows RDS to scale read operations?

A

Adding read replicas, which asynchronously replicate data from the primary instance.

68
Q

When is Aurora Serverless most useful?

A

For intermittent, unpredictable workloads like reporting databases or testing environments.

69
Q

What is a use case for RDS read replicas?

A

ffloading read-heavy traffic, such as business reporting or disaster recovery.

70
Q

How can you optimize DynamoDB for spiky traffic?

A

Use on-demand capacity mode to scale dynamically with traffic levels.

71
Q

Why use global secondary indexes in DynamoDB?

A

To distribute query load and reduce strain on the base table.

72
Q

What does “auto scaling” enable across all AWS databases?

A

Dynamically adjusting capacity to handle traffic changes without manual intervention.

73
Q

What are the main database scaling mechanisms across AWS services?

A

Aurora: Vertical (instance class) & Horizontal (read replicas, Aurora Serverless).
RDS: Vertical (instance/storage size) & Horizontal (read replicas).
DynamoDB: Horizontal (RCUs, WCUs, indexes), On-demand scaling.

74
Q

What are the four types of AWS load balancers?

A

Application Load Balancer (ALB), Network Load Balancer (NLB), Gateway Load Balancer (GWLB), and Classic Load Balancer (CLB).

75
Q

What key features are shared by all AWS load balancers?

A

High availability, automatic scaling, robust security, and health checks.

76
Q

What traffic types does an ALB handle?

A

HTTP and HTTPS.

77
Q

What routing features does an ALB provide?

A

Content-based routing using listener rules and algorithms like round-robin or least outstanding requests.

78
Q

What is the use of Automatic Target Weights (ATW) in ALB?

A

ATW optimizes traffic distribution across targets based on health metrics like 5XX error

79
Q

What traffic types does an NLB handle?

A

TCP, UDP, TCP_UDP, and TLS.

80
Q

What is the primary use case for an NLB?

A

Handling millions of requests per second with ultra-low latency.

81
Q

Can an NLB forward traffic to an ALB?

A

Yes, combining NLB and ALB features allows multi-protocol traffic handling.

82
Q

What is the main use case for a GWLB?

A

Improving security and compliance by routing traffic through virtual appliances like firewalls or intrusion detection systems.

83
Q

What protocol does a GWLB use to communicate with virtual appliances?

A

The GENEVE protocol.

84
Q

Why is the CLB considered outdated?

A

It provides basic load balancing and is recommended only if upgrading to ALB or NLB is not feasible.

85
Q

What is a listener in a load balancer?

A

A listener checks for connection requests using a specified protocol and port and routes traffic based on listener rules.

86
Q

What is a target group in a load balancer?

A

A collection of registered targets (e.g., EC2 instances) that receive traffic based on listener rules.

87
Q

What are health checks used for in a load balancer?

A

To monitor the health of registered targets and ensure traffic is only sent to healthy ones.

88
Q

How does SSL/TLS encryption work in load balancers?

A

The load balancer uses a certificate to decrypt frontend traffic; NLBs can also pass encrypted traffic directly to targets.

89
Q

How does an ALB achieve high availability?

A

By distributing traffic across EC2 instances in multiple Availability Zones and replacing unhealthy targets.

90
Q

How does Amazon RDS Multi-AZ improve high availability?

A

The primary database synchronously replicates data to a secondary database in another Availability Zone, ensuring failover.

91
Q

How can load balancers handle Availability Zone failures?

A

They route traffic only to healthy instances in operational zones.

92
Q

What combination of load balancers can improve high availability?

A

An external-facing ALB for public traffic and an internal-facing ALB for private traffic.

93
Q

What is the default routing algorithm for an ALB?

A

Round robin, with an option to use least outstanding requests.

94
Q

What makes NLBs suitable for volatile network traffic?

A

Their ability to handle millions of requests per second with low latency.

95
Q

What is the key advantage of using a GWLB?

A

Centralized traffic inspection and policy enforcement using third-party security appliances.

96
Q

What is the main benefit of integrating load balancers with Auto Scaling?

A

Automatically replacing unhealthy instances to maintain capacity and availability.

97
Q

What is Amazon Route 53?

A

A scalable Domain Name System (DNS) web service that provides domain registration, DNS routing, and health checks.

98
Q

What are the main routing options supported by Route 53?

A

Simple routing
Weighted routing
Latency routing
Failover routing
Geoproximity routing
Geolocation routing
Multivalue answer routing
IP-based routing

99
Q

What is a hosted zone in Route 53?

A

A container for DNS records that define how you want to route traffic for a specific domain or subdomain.

100
Q

What is the difference between public and private hosted zones?

A

Public hosted zones: Route internet traffic to AWS resources.
Private hosted zones: Route traffic within a VPC.

101
Q

What is simple routing in Route 53?

A

A basic configuration where a DNS query returns a single value, such as the IP address of a web server.

102
Q

What is weighted routing in Route 53?

A

Distributes traffic between resources based on assigned weights, allowing control over the proportion of traffic sent to each resource.

103
Q

What is latency routing in Route 53?

A

Routes traffic to the region with the lowest latency for the user, improving performance.

104
Q

How does failover routing work in Route 53?

A

Routes traffic to a secondary resource when the primary resource is deemed unhealthy based on health checks.

105
Q

What is geoproximity routing?

A

Routes traffic based on the geographic location of users and resources, with an option to adjust traffic flow using a bias value.

106
Q

How is geolocation routing different from geoproximity routing?

A

Geolocation routing: Routes based on the user’s geographic location (e.g., country or continent).
Geoproximity routing: Considers both user and resource location with optional bias adjustments.

107
Q

What is multivalue answer routing?

A

Returns multiple IP addresses for DNS queries, filtering out unhealthy resources to improve availability.

108
Q

What is IP-based routing?

A

Routes traffic based on user-IP-to-endpoint mappings, optimizing performance or reducing costs.

109
Q

What is the role of health checks in Route 53?

A

Monitors the health of resources and ensures traffic is routed only to healthy targets.

110
Q

How does Route 53 handle multi-region failover?

A

Routes traffic to a healthy resource in another region when a primary resource becomes unhealthy.

111
Q

What is an active-passive failover configuration?

A

Traffic is routed to primary resources by default and switches to secondary resources only if all primary resources are unhealthy.

112
Q

How can Route 53 create a tree of records for complex routing?

A

Combines multiple routing options (e.g., latency and weighted records) to route traffic based on multiple criteria.

113
Q

What is an A record in Route 53?

A

Maps a domain to an IPv4 address.

114
Q

What is an AAAA record in Route 53?

A

Maps a domain to an IPv6 address.

115
Q

What is a CNAME record in Route 53?

A

Maps a domain or subdomain to another domain or subdomain.

116
Q

What is an MX record in Route 53?

A

Specifies the mail servers for a domain.

117
Q

What is an NS record in Route 53?

A

Identifies the name servers for a hosted zone.

118
Q

How does Route 53 integrate with other AWS services for high availability?

A

Works with Elastic Load Balancing and Auto Scaling to distribute traffic and replace unhealthy instances.

119
Q

What is the Route 53 Resolver?

A

Responds recursively to DNS queries from AWS resources for public records, VPC-specific DNS names, and private hosted zones.

120
Q

How does Route 53 support content localization?

A

Geolocation routing directs traffic based on user location, allowing localized content delivery in preferred languages.

121
Q

How does Route 53 help with disaster recovery?

A

Enables multi-region failover configurations, routing traffic to healthy resources during outages.