EC2 Cheat Sheet

  • vCPU = Thread on a x86 physical core (other than t-series)
    • divide by 2 = number of physical cores
  • Nitro
    • A dedicated piece of hardware that offload storage, networking, security related operations from VMs, so VMs get more processing power
  • Instance Profile
    • A fancy name for an IAM role managed by the meta service of EC2
    • IAM role tokens are automatically acquired, encrypted, stored and renewed be the meta service, so the instance can have permissions defined in the role
  • Security
    • By default Linux instances only allow SSH access using key pairs
    • Key pairs can be created before and or when launching instances
    • The only time the private key can be downloaded is at creation, there is no way to retrieve it afterwards
    • There is no way to change key pairs using console or API after instance launch, but you may manually replace the public key in the operating system
    • Windows instances have pre-generated passwords that can be retrieved and must be changed after first login
    • By default instances have all ports blocked, you need to add instance to a security group and open ports you needed


  • On-demand
    • Billed by the hour or second depending on the OS
    • Instances are billed only when instance is in running state, instances in any another state are not billed
    • Minimum billing period is 1 hour / 60 seconds
      • Run a bill-by-hour instance for 30 mins, stop it, run for 30 mins again, you get a 2 hour bill

See Also

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