ELB-ASG - Elastic Load Balancing and Auto Scaling Groups Flashcards
What is the main purpose of High Availability in the Cloud?
a) Increase scalability
b) Application thriving even in case of disaster
c) Access on computers and smartphones
d) Handle greater loads by launching EC2 instances based on the demand
b) Application thriving even in case of disaster
High Availability means applications running at least in two AZs to survive a data center loss.
Which AWS offered Load Balancer should you use to handle hundreds of thousands of connections with low latency?
a) Application Load Balancer
b) Network Load Balancer
c) Elastic Load Balancer
b) Network Load Balancer
A Network Load Balancer can handle millions of requests per second with low-latency. It operates at Layer 4, and is best-suited for load-balancing TCP, UDP, and TLS traffic with ultra high-performance.
Changing an EC2 Instance Type from a t3a.medium to a t3a.2xlarge is an example of?
a) Horizontal scaling
b) High Availability
c) Agility
d) Vertical scaling
d) Vertical scaling
Vertical scaling means increasing the size of the instance. Changing from a t3a.medium to a t3a.2xlarge is an example of size increase.
What can you use to handle quickly and automatically the changing load on your websites and applications by adding compute resources?
a) An Elastic Load Balancer
b) A bigger instance type
c) An Auto Scaling Group
d) Health Checks on your EC2 instances
c) An Auto Scaling Group
An Auto Scaling Group (ASG) can automatically and quickly scale-in and scale-out to match the changing load on your applications and websites.
Which of the following statements is INCORRECT regarding Auto Scaling Groups?
a) Replace unhealthy instances
b) Are cost-effective by running at optimal capacity
c) Automatically register new instances to a load balancer
d) Automatically changing the EC2 Instances Types
d) Automatically changing the EC2 Instances Types
Auto Scaling Groups can add or remove instances, but from the same type. They cannot change the EC2 Instances Types on the fly.
Which Load Balancer is best suited for HTTP/HTTPS load balancing traffic?
a) Network Load Balancer
b) Classic Load Balancer
c) Elastic Load Balancer
d) Application Load Balancer
d) Application Load Balancer
Application Load Balancers are used for HTTP and HTTPS load balancing. They are the best-suited for this kind of traffic.
Which AWS service offers easy horizontal scaling of computing capacity?
a) EBS
b) AMI
c) IAM
d) ASG
d) ASG
Auto Scaling Groups (ASG) offers the capacity to scale-out and scale-in by adding or removing instances based on demand.
Which of the following statements is NOT a feature of Load Balancers?
a) Do regular health checks to your instances
b) Spread load across multiple downstream instances
c) Handle failures of downstream instances
d) Back-end autoscaling
d) Back-end autoscaling
Load Balancers cannot help with back-end autoscaling. You should use Auto Scaling Groups.
What are the types of scalability in the cloud?
There are 2 types which are:
- Vertical Scalability,
- Horizontal Scalability (=elasticity)
What does Vertical Scalability means?
Vertical Scalability means increasing the size of an instance.
Is very common for non distributed systems, such as a database.
There is a limit also on how much you can vertically scale due to hardware limits.
When the instance type is increased means scale up, when is decreased means scale down.
What does Horizontal Scalability means?
Horizontal Scalability means increasing the number of instances / systems for an application.
Horizontal Scaling implies distributed systems.
When the number of instances is increased meand scale out, when the number is decreased means scale in.
What is scalability?
Is the ability to accomodate a larger load by making the hardware stronger (scale up) or by adding nodes (scale out)
What is elasticity?
Applied to the cloud, it means that once a system is scalable, elasticity means that there will be some “auto-scaling” so the system can scale based on the load.
It allows to pay-per-use, match demand and optimize costs.
What are load balancers?
Load balancers are servers that forward internet traffic to multiple servers (EC2 instances) downstream.
Why to use a load balancer?
Because a load balancer:
- Spread load accross multiple downstream instances
- Exposes a single point of access (DNS) for an application.
- Seamlessly handle failures of downstream instances.
- Perform regular healthchecks to instances.
- Provide SSL termination (HTTPS) for websites.
- Provides high availability across zones.
