EC2 – Associate

Question 1

Three things that make a public network what it is:

Answer 1

Public IP:

• The machine can be identified on the internet (WWW)
• Unique IP across the whole web (not two machines can have the same public IP).
• Can be geo-located easily

Question 2

Five things that make a public network what it is

Answer 2

• The machine can only be identified on a private network only
• The IP must be unique across the private network
• Different private networks can have the same IPs.
• Machines connect to WWW using a NAT + internet gateway (a proxy)
• Only a specified range of IPs can be used as private IP

Question 3

What is Elastic IP?

How many instances can it be attached to?

Answer 3

An Elastic IP is a public IPv4 IP you own as long as you don’t delete it

You can attach it to one instance at a time

Question 4

How many Elastic IPs come with my account by default?

What can i do if i will need more?

Answer 4

You can only have 5 Elastic IP in your account

You can ask AWS to increase that.

Question 5

Try to avoid using Elastic IP - Why??

What can replace Elastic IP?

Answer 5

• They often reflect poor architectural decisions
• Instead, use a random public IP and register a DNS name to it
• When you use a Load Balancer and don’t use a public IP

Question 6

Private and public network:

What EC2 comes with by default?

Answer 6

By default, your EC2 machine comes with:

• A private IP for the internal AWS Network
• A public IP, for the WWW.

Question 7

What are the placement group strategist?

(CSP)

Answer 7

• Cluster—clusters instances into a low-latency group in a single Availability Zone
• Spread—spreads instances across underlying hardware (max 7 instances per group per AZ)
• Partition—spreads instances across many different partitions (which rely on different sets of racks) within an AZ. Scales to 100s of EC2 instances per group (Hadoop, Cassandra, Kafka)

Question 8

What is a Placement group?

Answer 8

a placement group is just a group - AWS instances that exist within a common AZ can be grouped into a placement group.

Where group members are able to communicate with one another in a way that provides low latency and high throughput.

Question 9

When to use Placement Groups Cluster?

Answer 9

Cluster as a great network so:

• Big Data job that needs to complete fast
• Application that needs extremely low latency and high network throughput

Question 10

When to use Placement Groups Spread?

Answer 10

Placement Groups Spread Can spread across AZ This Reduced risk is simultaneous
failure because they are on different physical hardware

When to use:

• Application that needs to maximize high availability
• Critical Applications where each instance must be isolated from failure from each other

Question 11

When to use Placements Groups Partition?

Answer 11

• HDFS
• HBase
• Cassandra
• Kafka

Question 12

ENI

Answer 12

Elastic Network Interfaces

Question 13

What is ENI?

Answer 13

Elastic Network Interfaces

logical component in a VPC that represents a virtual network card

Question 14

Which attributes can the ENI have?

Answer 14

• Primary private IPv4, one or more secondary IPv4
• One Elastic IP (IPv4) per private IPv4
• One Public IPv4
• One or more security groups
• A MAC address

Question 15

One con and one floes of ENI?

Answer 15

• You can create ENI independently and attach them on the fly (move them) on EC2 instances for failover.
• Bound to a specific availability zone (AZ)

Question 16

On EC2 instance, what does it mean “Stop” and “Terminate”?

Answer 16

• Stop – the data on disk (EBS) is kept intact in the next start
• Terminate – any EBS volumes (root) also set-up to be destroyed is lost

Question 17

What happen when EC2 Hibernate?

what is needed (must)?

Answer 17

• The in-memory (RAM) state is preserved
• The instance boot is much faster!
• (the OS is not stopped / restarted)
• Under the hood: the RAM state is written to a file in the root EBS volume
• The root EBS volume must be encrypted

Question 18

When we use EC2 hibernet?

Answer 18

• Long-running processing
• Saving the RAM state
• Services that take time to initialize

Question 19

What is EC2 Nitro?

Answer 19

• Next generation of EC2 instances
• New virtualization technology
• Allows for better performance:
  • Better networking options (enhanced networking, HPC, IPv6)
  • Higher Speed EBS (Nitro is necessary for 64,000 EBS IOPS – max 32,000 on non-Nitro)
• Better underlying security

Question 20

When to use EC2 Capacity Reservations?

Answer 20

• To ensure you have EC2 Capacity when needed
• Manual or planned end-date for the reservation
• No need for 1 or 3-year commitment
• Capacity access is immediate, you get billed as soon as it starts

Question 21

What is the EC2 Capacity Reservations specify?

Answer 21

• The Availability Zone in which to reserve the capacity (only one)
• The number of instances for which to reserve capacity
• The instance attributes, including the instance type, tenancy, and platform/OS