Fundamentals of AWS (Part 1) Flashcards
If you want control over the EC2 Instance placement strategy? This is called what?
Placement Groups
What’s the difference between IAM Users, Groups and Roles?
Users: Usually a physical person.
Groups: Functions (admins, devops) Teams (engineering, design…) Contains users!
Roles: Internal usage within AWS resources.
How many roles per application?
One
What port does AWS use for SSH?
Port 22
Security Groups are the fundamental of what type of security in AWS?
Network Security
How are security groups used for EC2?
They control how traffic is allowed into or out. They act as a firewall.
What all do security groups regulate?
- Access to Ports.
- Authorised IP ranges – IPv4 and IPv6
- Control of inbound network (from other to the instance)
- Control of outbound network
Can a security group be attached to multiple instances or only 1?
Multiple Instances
T / F: Security Groups are locked down to a region / VPC combination
T
If you experience a time out when trying to access your application. This it most likely due to what?
Security Group Issue
If you recieve a “connection refused” error, then what’s likely going on?
It’s an application error or it’s not launched.
T/F: For security Groups, all inbound traffic is blocked by default?
True
T/F: For security Groups, all outbound traffic is blocked by default?
False. It’s authorized
Public IP means the machine can be identified where?
On the internet
Private IP means the machine can be identified where?
Only on a private network.
How to private IP machines connect to the internet?
Using an internet gateway (a proxy)
T / F: When you stop and start an EC2 instance, it’s public IP remains constant?
False - It can change its public IP
This will provide you a fixed public IP for your instance
Elastic IP
An Elastic IP is a what kind of IP?
public IPv4
How many instance can you attach an Elastic IP too?
One
How many Elastic IPs can you have by default
5
By Default, your EC2 machine comes with what set of IPs if any?
Public, for www
Private IP for the internal AWS network.
T /F: When SSH’ing into our EC2 instance, we use the private IP.
False. We use the public because we are not on the same network to use private.
EC2: You can bootstrap an instance using ___?
EC2 User Data script
What does bootstraping mean?
Means launching commands when a machine starts.
The EC2 User Data Script runs with what user?
Root user
What are the 4 EC2 Instance Launch Modes?
On demand
Reserved
Spot Instances
Dedicated Hosts
Describe On Demand Instances?
short workload, predictable pricing
Reserved Instances
long workloads (>= 1 year)
Spot Instances
short workloads, for cheap, can lose instances
Dedicated Hosts
book an entire physical server, control instance placement
Dedicated Instances
no other customers will share your hardware
Describe ‘On Demand EC2 Instance’
- Pay for what you use (billing per second, after the first minute)
- Has the highest cost but no upfront payment
- No long term commitment
In what case should you use EC2 On Demand Instances?
Recommended for short-term and un-interrupted workloads, where you can’t predict how the application will behave.
Reservation period for a ‘Reserved Instance’ can be what?
1-3 years
Can receive up to __ percent discount on Reserved Instances compared to On-demand
75%
This type of instance is recommended for steady state usage applications?
Reserved Instances
Can receive up to __ percent discount on Spot Instances
90%
This type of Instance allows you to bid a price and get the instance as long as its under the price
Spot Instance
This type of instance is good for batch jobs, big data analysis, or workloads that are resilient to failures
Spot Instances
This type of instance is useful for software that have complicated licensing model (BYOL) or for companies that have strong regulatory or compliance needs.
EC2 Dedicated Hosts
It’s now possible to have an unlimited burst credit balance for burstable EC2’s
True
T2 / T3 what what kind of EC2 Instances?
Burstable
What’s an AMI?
an image to use to create our instances
T / F: AMI’s can be used in multiple regions?
False. AMIs are built for a specific AWS region.
What are the two strategies for placement groups?
Cluster, Spread
Describe Cluster Placement Group
Cluster—clusters instances into a low-latency group in a single Availability Zone
Application that needs extremely low latency and high network throughput could make use of this>
Placement Groups Cluster. Great network (10Gbps bandwith btw instances)
Cons: If rack fails, all instances fail.
How man EC2 Instances are allowed per AZ placement group?
7
Placement Groups can span across AZ’s?
True
EC2 instances are billed by the?
Second
