What is EC2 instances families?
An EC2 instance family is the AWS classification for different kinds of hardware/software optimizations for EC2 instances.
What is an EC2 type?
An EC2 instance type represents the hardware/software optimization and its specifications in a EC2 instance.
Example: t2.micro.
General purpose family examples
M5, T2, T3 and T4g
Compute optimized family examples
C5, C6
Memory optimized families examples
R5, R6i
What is a root volume?
Root volumes are EBS volumes that contains the image to boot an EC2 instance.
Root volumes by default are excluded in instance termination.
What is an instance store volume?
An instance store is an EC2 storage type in which temporary storage is provided. The storage is physically attached to the instance and provides high performance.
Storage is persistent only during EC2 execution time. After restart or stop, all data is wiped out.
Where do EBS volumes live?
In AWS availability zones.
In order to transfer them, a snapshot is required.
What is EC2 instance metadata?
Metadata are EC2 instance information that can be accessed from within the EC2 instance.
The endpoint is 169.254.169.254/latest/meta-data
What is the difference between IMDSv1 and IMDSv2?
The first version of Instance Metadata does not require any authentication token. Metadata direct access is allowed.
The IMDSv2 requires a session token to be provided when consuming instance metadata. The token can be obtained from a PUT request in 169.254.169.254/latest/api/token.
IMDSv2 is a session-oriented method to obtain instance metadata.
What is EC2 Placement Groups?
A placement group is an EC2 feature that manages the physical deploy location of EC2 instances across or within availability zones.
They are mainly used to let EC2 instances very close or very far between each other.
List the existent placement groups strategies
- Cluster;
- Spread;
- Partition.
Explain the cluster placement group strategy.
It packs EC2 instances very close together within an availability zone.
Explain the Partitioned placement group strategy
This strategy is used when there’s the need of unique hardware within availability zones for different groups of EC2 instances
Explain the Spread placement group strategy
Places a small number of EC2 instances across distinct underlying hardware.
Cluster placement group typical use case
HPC and tightly coupled applications that require low latency with node to node communication.
Use case for partition placement groups
Large and distributed workloads like Kafka, Cassandra and Hadoop.
Use case for spread partition groups strategy
This should be the option when a small number of instances offers critical applications. This reduces the likelihood of simultaneous failures.
Where do live ENIs? Can a resource have more than one? Under which conditions?
ENIs are attached to subnets.
Yes, but only if the same availability zone is used for all ENIs.
All types of ENIs
- Elastic Network Interfaces;
- Elastic Network Adapters;
- Elastic Fabric Adapters.
ENIs vs ENAs vs EFAs
- ENIs can be attached to any instance type;
- ENAs provide enhanced networking capabilities with Nitro and other instances;
- EFAs are good for ML and HPC applications
What is one requirement for using NAT instances?
Disabling source//destination checks.
What is source and destination checks?
This is a property in EC2 instances that makes them check if any source or destination traffic is generated from/for the instance itself.
Disabling it allows traffic forwarding
What is the Nitro System?
Nitro is the underlying infrastructure for all modern EC2 instances, increasing security and performance.
Nitro uses specialized hardware and software.
