Quiz Flashcards
What is Cloud Computing?
On demand delivery of IT resources over the internet with pay-as-you go pricing.
What is IaaS?
Infrastructure as a service.
Access to networking, compute, and storage. You manage patching, upgrades and administration.
What is PaaS?
Platform as a service.
Access to managed services. AWS manages patching, upgrades, and some degree of admin.
What is SaaS?
Software as a service.
Access to complete applications. The application is managed by AWS. For example, when a new feature appears for Email, Amazon adds it, not the customer.
What are the cloud computing deployment models?
Cloud
Hybrid
On-premises (private cloud)
What are the benefits of cloud computing?
Trade up-front expense for variable expense
Save on operating IT infrastructure
No need to guess the capacity
Take advantage of economies of scale
Increase speed and agility
Go global instantly
What are the drawbacks of on-prem compute resources?
The time and money it takes to get up and running with on-premises resources is fairly high.
Research to see what type of servers you want to buy
How many you’ll need
Purchase that hardware up front
Wait for multiple weeks or months for a vendor to deliver those servers to you. You then
take them to a data center
Own or rent the datacenter
Install them
Power them
Secure them
Host your applications on top of these servers
Once you buy these servers you are stuck with them whether you use them or not.
What is EC2?
Elastic Compute Cloud
You need raw computing capacity to host your applications and provide the computing power that your business needs. When you’re working with AWS, those servers are virtual. The service you use to gain access to virtual servers is called EC2.
Explain how EC2 uses virtualization.
EC2 runs on top of physical host machines managed by AWS using virtualization technology.
A hypervisor running on the host machine is responsible for sharing the underlying physical resources between the virtual machines.
This idea of sharing underlying hardware is called multitenancy.
The hypervisor is responsible for coordinating this multitenancy and it is managed by AWS.
The hypervisor is responsible for isolating the virtual machines from each other as they share the resources of the host.
When you provision an EC2 instance, you can choose the operating system based on either Windows or Linux.
Explain the different instance families available through EC2.
general purpose (balance of CPU, Memory, Storage, and IO)
application servers
gaming servers
backend servers for enterprise applications
small and medium databases
compute optimized (more powerful CPU)
high-performance web servers
compute-intensive applications servers
dedicated gaming servers
batch processing workloads that require processing many transactions in a single group
memory-optimized (more high-speed volatile memory)
workloads that process large datasets in memory
accelerated computing (has outboard GPU)
floating-point number calculations
graphics processing
data pattern matching
and storage optimized (fast IO to faster and bigger drives)
high, sequential read and write access to large datasets on local storage
distributed file systems
data warehousing applications
high-frequency online transaction processing (OLTP) systems.
any application that require high input/output operations per second (IOPS)
Explain Amazon EC2 pricing.
On Demand
you only pay for the duration that your instance runs
can be per hour or per second, depending on the number, instance family and size , OS , and tenancy in a region.
Savings Plan ( <72% Savings)
offers low prices on EC2 usage in exchange for a commitment to a consistent amount of usage measured in dollars per hour for a one or three-year term
Reserved Instances (<75% Savings)
suited for steady-state workloads or ones with predictable usage
You qualify for a discount once you commit to a one or three-year term
Three payment options
Up-front
Partial up-front
No up-front
Spot Instances (<90% savings)
AWS can reclaim the instance at any time they need it, giving you a two-minute warning to finish up work and save state, giving you a two-minute warning to finish up work and save state.
Dedicated Host
meeting certain compliance requirements
nobody else will share the tenancy
What is the key difference between the reserved instance and savings plan billing models?
The primary difference between AWS Reserved Instances and Savings Plan is that Reserved Instances are based on a commitment to use a specific instance type at a fixed price for a specified period, while Savings Plans are based on a commitment to spend a specific dollar amount per hour on any EC2 instance type over a specific period.
What is Scalability and what is Elasticity? Contrast the two concepts.
Scalability is a question of how much more processing power we can add. Elasticity is a question of how quickly we can add power and remove processing power. One is a question of how big or small we can go, the other is a question of how quickly we can get to those capacities.
What are the two ways you can scale up an instance? Are there any limitations to the ways in which we can scale up?
There are two ways to scale up EC2 instances.
1. Add more resources to an instance (Vertical Scaling)
2. Create more instances (Horizontally Scaling)
Sometimes adding more resources to an instance doesn’t solve the problem because you need to process in parallel. In this case horizontal scaling can help.
What is a load balancer and what problem does it solve?
When you have multiple EC2 instances all running the same program, to serve the same purpose, and a request comes in, how does that request know which EC2 instance to go to? How can you ensure there’s an even distribution of workload across EC2 instances? So not just one is backed up while the others are idle sitting by. You need a way to route requests to instances to process that request. What you need to solve this is called load balancing.
A load balancer is an application that takes in requests and routes them to the instances to be processed.
Key Point: A load balancer decides how to distribute the load, not how many instances are necessary. The latter is a function of the auto-scaling group.
