EC2 - Solutions Architect Associate Level Flashcards by Xaris A

What are the two IP types?

IPv4 & IPv6

IPv4: 1.160.10.240
IPv6: 1900:4545:3:200:f8ff:fe21:67cf

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Public IP

IP that is accessible over the internet

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Private IP

Is IP within a private Network (e.g. company) and ONLY the machines inside that network can talk to each other

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Internet Gateway (Public)

Allows machines in a private network to communicate with machines (servers) outside of that private network using the internet.

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What does a Public IP need to be across the whole web?

Unique - no two machines can have the same public IP

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Can public IP be geo-located easily?

Yes

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Private IP uiniqueness

Needs to be unique within its private network

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Can two different private networks (two companies) have the same IPs?

Yes - Machine 1 from Network A can have the same IP as Machine 1 from Network B

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What do machines in a private network need to access the public internet?

NAT (network address translation) & Internet gateway (proxy)

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What is a Network Address Translation (NAT)

A way to map multiple private IPs inside a local network to a public IP address before transferring the information onto the internet

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True/False - Only a specified range of IPs can be used as private IP

True

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What happens when you stop and start an EC2 instance?

It’s IP can change

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What is an elastic IP?

It is a fixed public IP - an IPv4 IP you own as long as you do not delete it

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Can you attach an Elastic IP to many instances at a time?

No - only to one

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How many Elastic IP’s can you have in your AWS acc?

5 (can ask for more)

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What can you do with Elastic IPs when a failure of an instance/software occurs?

Rapidly remap the address to another instance in your account

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What does your EC2 machine come with automatically when created?

Public & Private IP

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Can you use a private IP when SSH?

No - only public IP

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What are Placement Groups?

It is a way of using an EC2 placement Strategy within an AZ

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What do you specify when you create a placement group?

The strategy you want
i.e.
Cluster
Spread
Partition

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What is the Cluster Strategy of a Placement Group?

Cluster instances into a low-latency group in a single AZ

What is the Spread Strategy of a Placement Group?

Spread instances across underlying hardware (max 7 instances per group per AZ) - for critical apps

What is the Partition Strategy of a Placement Group?

Spread instances across many different partitions (which rely on different sets of racks) within an AZ. Scales to 100s of EC2 instances per group.

Good for Hadoop, Cassandra, Kafka

What is the Cluster Placement Group Architecture?

All EC2 instances are on the same Rack (hardware) and are all in the same AZ

What are the Pros of having a Cluster Placement Group?

Great Network (10 Gbps bandwidth between instances) Low latency

Cons of using a Cluster Placement Group?

If the rack fails, all instances fail at the same time

Use cases of Cluster Placement Groups?

Big Data job that need to be completed fast Apps that require low latency and high network throughput

Spread Placement Group Architecture

You minimise the risk by locating all EC2 instances on different hardware (racks) across multiple AZs

Pros of Spread Placement Group Architecture

Span across AZ Reduced risk in simultaneous failure Instances are on different physical hardware

Cons of using Spread Placement Group Architecture

Limited to 7 instances per AZ per placement group

Use Case of Spread Placement Group

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

Architecture of Partition Placements Group

You can have 2 partitions in AZ 1 and another partition in AZ 2. Each partition (rack) has many EC2 instances.

Pros of Partition Placement Groups

Up to 7 partitions (racks) per AZ Span across multiple AZ in the same region Up to 100s of EC2 instances Instances in one partition do not share the same rack with another partition Failure is isolated to each partition EC2 instances get access to the partition information as metadata

Use cases of Partition Placement Groups

Big Data Applications i.e. HDFS, HBase, Cassandra, Kafka

What is an Elastic Network Interface (ENI)

Logical component in a VPC that represents a virtual network card

Elastic Network Interface (ENI) attributes

Primary private IPv4, one or more secondary IPv4 One elastic IP (IPv4) per private IPv4 One Public IPv4 One or more sec groups A MAC address

Can ENI be created independently and attached on the fly on EC2 instances?

Yes

What is the benefit of attaching an ENI to an EC2 instance on the fly?

Helps with failover

Are ENI global?

No - they are bound to specific AZ

Why would you move an ENI?

In case of a fail over

If you have an ENI created with an EC2 instance and then you delete the EC2 instance, what happens to the ENI?

It also gets deleted/terminated

What happens to the EBS volume if you STOP the EC2?

It is kept intact

What happens to the EBS volume if you TERMINATE the EC2?

It gets deleted

What happens when you Hibernate an EC2 instead of stopping/terminating?

RAM Memory state is preserved Instance boot is much faster Just goes to sleep

What happens to RAM of the EC2 when it hibernates?

It gets written into the EBS volume - meaning it needs to be encrypted and have enough space for the RAM to be written

Hybernation architecture/process

You have an EC2 with Ram and EBS volume (encrypted You hibernate, the RAM pops into the EBS, and the EC2 instance is stopped. Then when you start again, the RAM goes back into the EC2

Use cases of Hibernation

Long running processes Saving RAM state Services that take time to initialise

Hibernation good to know

Supports lots of instances Must be less than 150GB RAM Not support bare metal Root volume EBS must be encrypted Available on demand, reserved, spot instances

How long can an EC2 instance be hibernated for?

No more than 60 days

Which EC2 Placement Group should you choose if you have a critical application hosted on a fleet of instances in which you want to achieve a maximum availability when there is an AZ failure?

Spread Placement Group - spread your instances on different physical hardware across different AZs