AWS EC2 INTERVIEW QUESTION-1

What is AWS EC2?
  • Amazon Elastic Compute Cloud (Amazon EC2) is a web service that provides resizable compute capacity in the cloud.
  • It is designed to make web-scale computing easier for developers
  • You are limited to running up to a total of 20 On-Demand instances across the instance family, purchasing 20 Reserved Instances, and requesting Spot Instances per your dynamic spot limit per region (by default)
  • Amazon EC2 currently supports a variety of operating systems including: Amazon Linux, Ubuntu, Windows Server, Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Fedora, Debian, CentOS, Gentoo Linux, Oracle Linux, and FreeBSD
  • EC2 compute units (ECU) provide the relative measure of the integer processing power of an Amazon EC2 instance
  • With help of EC2 you have full control at the operating system layer

Summary:

  • Virtual computing environment (known as instances)
    • Pre-configured templates for your instances (known as Amazon Machine Images – AMIs)
    • Amazon Machine Images (AMIs)
    • Amazon EC2 provides various configurations of CPU, memory, storage and networking capacity for your instances (known as instance type)
    • Secure login information for your instances using key pairs
    • Storage volumes of temporary data is deleted when you stop or terminate your instance (known as instance store volumes)
    • Amazon EC2 provides persistent storage volumes (using Amazon Elastic Block Store – EBS)
    • A firewall that enables you to specify the protocols, ports, and source IP ranges that can reach your instances using security groups
    • Static IP addresses for dynamic cloud computing (known as Elastic IP address)
    • Amazon EC2 provides metadata (known as tags)
    • Amazon EC2 provides virtual networks that are logically isolated from the rest of the AWS cloud, and that you can optionally connect to your own network (known as virtual private clouds – VPCs)
Lets assume you have deployed an application on Amazon EC2 that call AWS APIs. How will you pass credentials to the application securely.

We always use IAM roles when It is an AWS EC2. Best practice not to store API credentials within applications, on file systems or on instances (such as in metadata).

Amazon Elastic File System (Amazon EFS) provides simple, scalable, elastic file storage for use with AWS Cloud services and on-premises resources. You have decided to use EFS for sharing files across many EC2 instances and you want to be able to tolerate an AZ failure. What should you do?

Correct Answer: We can Create EFS mount targets in each AZ and configure each EC2 instance to mount the common mount target.

You are architecting a complex application landscape that values fast disk I/O for EC2 instances above everything else. Which storage option would you choose?

Correct Answer: Instance Store

You notice that you cannot ping an EC2 instance that you recently started in a public subnet. What could be the problem?