EC2 Flashcards
What is AMI?
An AMI (Amazon Machine Image) is a template that contains the software configuration (operating system, application server, and applications) required to launch an EC2 instance
Permissions required on the private key (pem file)
0400
Default policy for inbound traffic in a security groups
Deny all
Default policy for outbound traffic in a security group
Allow all
What is an Elastic IP?
a static public IPv4 IP designed for dynamic cloud computing.
are Elastic IPs region specific or global?
region specific
command used to start services in an Amazon Linux 2 machine
systemctl
Whats bootstrapping?
Launching commands when the machine starts
what user is used to run the bootstrap routine?
root
What is the EC2 User data?
Data used to perform common automated configuration tasks and even run scripts after the . EC2 instance starts
What types of used data can you pass to Amazon EC2?
shells scripts and cloud-init directives
When are the user data scripts run?
By default they are only run during the boot cycle when you first launch an EC2 instance
Where is the user data script copied to for execution?
it is copied to the directory /var/lib/cloud
Why should you delete the user data script from the EC2 instance?
If you were to create an AMI from the EC2 instance and the user data was not deleted, then the script would be executed for every EC2 instance created from the resulting AMI
You pay for an EC2 instance compute component only when it’s in “running” state or also when it is on “stopped” state?
Only when it is in “running” state
Security Groups can reference all of the following except:
- IP address
- CIDR block
- Security Group
- DNS name
DNS name
What security groups are locked down to?
- a region
- a vpc
- a region/vpc combination
a region/vpc combination
What does EC2 stand for?
Elastic Compute Cloud
EC2 Instance Purchasing Options
- On-demand instances
- Reserver Instances
- Scheduled Instances
- Spot instances
- Dedicated Hosts
- Dedicated Instances
- Capacity Reservations
What is an on-demand instance?
it is an EC2 instance purchasing option where you pay bay the second for the instances that you launch
Whats is a Reserved Instance?
EC2 instance purchasing option where you pay for a term from one to three years
What is a Scheduled Instance?
EC2 instance purchasing option where the instance are always available on the specified recurring schedule, for a one-year term
What is a Spot instance?
EC2 instance purchasing option where you request unused EC2 instances
Whats a dedicated host?
EC2 instance purchasing option where you pay for a physical host that is fully dedicated to run you EC2 instances
What is a dedicated instance?
EC2 instance purchasing option where you pay by the hour, for instances that run in a single-tenant hardware
What is Capacity Reservation?
EC2 instance purchasing option where you reserve capacity for your EC2 instances in a specific Availability Zone for any duration
EC2 R instance type
Instances for applications that need a lot of RAM - in memory caches
EC2 C instance type
Instances for applications that need good CPU - compute/databases
EC2 M instance type
Instances for applications that are balanced - general/web app
EC2 I instance type
Instances for applications that need a good local I/O (instance storage) - databases
EC2 G instance type
Instances for applications that need GPU - video rendering/machine learning
EC2 T2/T3 Instance type
Burstable instances
EC2 T2/T3 - unlimited instances type
Unlimited burst
Are custom AMI available region-wise or globally?
Region-wise
What type of placement groups there exist for EC2 instances?
Cluster and Spread
Cluster placement group
- Have great network speed (10 Gb)
- All EC2 instances in a Cluster are in the same Rack (same hardware/Availability Zone)
Use cases:
- BigData job that needs to be completed fast
- Applications that need extremely low latency and high network throughput
Spread placement group
- All EC2 instances are located in different hardware
- Can span across multiply Availability Zones
- Reduced risk of simultaneous failure
- Limited to 7 instances per AZ per placement group
Use case:
- Application that needs to maximize high availability
- Cassandra Cluster, Kafka, Clustered Web Application that is distributed
EC2 instances that can not be instantiated in a placement group
T2
Difference between Cluster and Spread placement groups
Clusters
- have great network speed (10 Gb)
- All EC2 instances in a Cluster are in the same Rack (same hardware/Availability Zone)
