Guidelines to choose the right EC2 Instance

EC2 instances are classified based on the category. The criteria to choose EC2 types is CPU, meory,storage and networking capacity etc.
Compute optimized: c3.*, 4.* , cpu intensive db, web applications.

General purpose- a1.*, t1.*,t2.*,m3.*, .m4.* t1/t2- lowest. m3/m3 low medium.

Memory optimized-r4.*, x1e.*,

Storage optimized- d2.*, i3.*   D2 - I2- no sql , File system, data warehouse.hadoop

Accelerated computing-  P3/P2/Inf1/G4/G3/F1.  Grapphics processing unit. Streaming,m/c learning, video encoding.

  EBS optimized instances-  Ec2 that depends high IOPs throughput.

Breakeven CPU usage :  Point at which a burstable performance instance costs the same as a fixed performance instance.

T3, T3a, and T2: Burstable Performance Instances

 - Suited for wide range of general-purpose application

- Usage credit for CPU usage.

 - Designed to provide a baseline level of CPU performance with the ability to burst to a higher level when required by your workload

- If configured as unlimited, it can sustain high CPU performance for any period of time as required.

 M5, M5a, M5ad, M5d, M5dn, and M5n Instances - offering a balance of compute, memory, and networking resources for a broad range of applications

Vulnerabilibility Scan:
allowed, but you need to take permission in advance from AWS and that can be done only in your instances.

The EC2 config service runs as a local system and performs various functions to prepare an instance when it first boots up.

In hibernation,
- you pay only for the EBS volumes and Elastic IP Addresses attached to it; there are no other hourly/compute charges (just like any other stopped instance).
-After bringing back to running state, private IPv4 and v6 retained. Public ipv4 released and assiged a new one.

Rule of Thumb

Average CPU usage over a 24-hour < breakeven CPU usage

à use a burstable performance instance in unlimited mode so that you can benefit from the lower price of a burstable performance instance while getting the same performance as a fixed performance instance.

Average CPU usage over a 24-hour > breakeven CPU usage

à the burstable performance instance will cost more than the equivalently-sized fixed performance instance.