VPCs Flashcards

1
Q

What does VPC stand for?

A

Virtual Private Cloud

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2
Q

What is a VPC?

A
  • Think virtual data center in the cloud
  • A logically isolated section of AWS where you can launch AWS resources in a virtual network that you define
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3
Q

What can you do with a VPC?

A
  • Launch instances into a subnet of your choosing
  • Assign custom IP address ranges in each subnet
  • Configure route tables between subnets
  • Create Internet Gateway and attach it to our VPC
  • Much better security control over your AWS resources
  • Instance security groups
  • Subnet Network Access Control Lists
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4
Q

What is VPC Peering?

A
  • Allows you to connect one VPC with another via a direct network route using private IP addresses
  • Instances behave as if they were on the same private network
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5
Q

Can VPC Peering be done between two VPCs in different AWS accounts?

A

Yes

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6
Q

Suppose VPC A is peered with VPC B, and VPC B is paired with VPC C. Is VPC A considered peered with VPC C?

A

NO. VPC Peering is NOT transitive!

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7
Q

Can you use VPC Peering to peer two VPC in different AWS regions?

A

Yes

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8
Q

What does IGW stand for?

A

Internet Gateway

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9
Q

What are the key components of a VPC?

A
  • Gateway (IGW or Virtual Private Gateway)
  • Route Tables
  • Network Access Control Lists
  • Subnets
  • Security Groups
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10
Q

Can you have two VPC subnets in the same AZ?

A

Yes

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11
Q

Can you have a subnet stretched across multiple AZs?

A

No

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12
Q

When you create a VPC, what infrastructure is created by default?

A
  • A Default Route Table
  • A Network ACL
  • A Default Security Group

(Note that it does NOT create subnets or IGWs)

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13
Q

If I launch a VPC into US-East-1a in my account, and someone else launches a VPC into US-East-1a in their account, does this mean the two VPCs are in the same AZ?

A

Not necessarily, The AZ’s are randomized

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14
Q

How many IP Addresses does Amazon Reserve per subnet?

A

5

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15
Q

What is the maximum number of IGWs you can have per VPC?

A

1

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16
Q

Can you have a security group spanning multiple VPCs?

A

No

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17
Q

Can you create an ELB with only one public subnet?

A

No, to create an ELB you need at least 2 public subnets

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18
Q

What is a Bastion Host?

A

A hardened, secure request forwarder allowing you to SSH/RDP in to private subnets in order to administer them (Idea is about lowering surface area of attack)

19
Q

Can you use a NAT Gateway as a Bastion Host?

A

No

20
Q

Are Bastion Hosts usually placed in a private subnet or a public subnet?

A

They are placed in a public subnet so you can access the private subnet

21
Q

What is Direct Connect and what are its primary use cases?

A
  • Idea is that it directly connects your data center to AWS
  • Useful for high throughput workloads (lots of network traffic)
  • Useful if you need a stable and reliable secure connection
22
Q

What are the steps for setting up AWS Direct Connect?

A
  1. Create a virtual interface in the direct connect console. This is a PUBLIC virtual interface
  2. Go to the VPC Console and then to VPN Connection. Create a Customer Gateway
  3. Create a Virtual Private Gatway
  4. Attach the Virtual Private Gateway to the desired VPC
  5. Select VPN Connections and create a new VPN Connection.
  6. Select the Virtual Private Gateway and the Customer Gateway
  7. Once the VPN is available, set up the VPN on the customer gateway or firewall
23
Q

What is AWS Global Accelerator?

A

A service in which you create accelerators to improve availability and performance of your applications for local and global users

24
Q

How many static IP addresses does AWS assign to you for Global Accelerator?

A

2

(Note you can also bring your own static IPs!)

25
Q

How do you control traffic in AWS Global Accelerator?

A

Use traffic dials. This is done within an endpoint group

26
Q

What is a VPC Endpoint?

A

A VPC Endpoint enables you to privately connect your VPC to supported AWS Services and VPC endpoint services powered by PrivateLink without requiring an internet gateway, NAT device, VPN Connection, or Direct Connect Connection

27
Q

What are the two types of VPC Endpoints?

A
  • Interface Endpoints
  • Gateway Endpoints
28
Q

For what services are VPC Gateway Endpoints supported?

A
  • Amazon S3
  • DynamoDB
29
Q

Suppose you want to peer a VPC with tens or thousands of other customer VPCs. What is the best way to accomplish this?

A

AWS PrivateLink

30
Q

Does AWS PrivateLink require VPC Peering?

A

No.

There’s no NAT, no route tables, no IGWs, etc.

31
Q

What is required to use AWS PrivateLink?

A
  • A Network Load Balancer on the service VPC
  • An ENI on the customer VPCs
32
Q

What is AWS Transit Gateway used for?

A
  • It allows you to have transitive peering between thousands of VPCs and on-premises data centers
  • Think simplify network topology
  • Always works on a hub-and-spoke model
33
Q

Can you use AWS Transit Gateway across multiple regions?

A

Yes

34
Q

Can you use AWS Transit Gateway across multiple accounts?

A

Yes

35
Q

Do AWS Transit Gateways work with Direct Connect?

A

Yes

36
Q

When using AWS Transit Gateways, how can I limit how VPCs talk to one another?

A

Use route tables

37
Q

What is the ONLY AWS Service that supports IP Multicast?

A

AWS Transit Gateway

38
Q

What is the use case for AWS VPN CloudHub?

A
  • Connecting multiple sites, each with a VPN Connection, together over a hub-and-spoke model
  • It operates over the public internet, but all traffic between the customer gateways and the VPN CloudHub is encrypted
39
Q

When using VPCs, will private IPs or public IPs produce a lower network cost? Why?

A

private IPs are less expensive than public IPs, because private IPs use the AWS Backbone Network

40
Q

In general, does AWS charge you more/less/or the same for communicating between VPCs in different AZs within the same region vs. communicating between VPCs in different regions?

A

communicating between VPCs in different AZs in the same region is less expensive than communicating between VPCs in different regions.

41
Q

How can you use VPCs and cut all network costs? What is the problem with that approach?

A
  • Use private IP addresses
  • group all EC2 instances in a single AZ
  • This is a problem because it leaves a single point of failure
42
Q

What is the definition of a public subnet?

A

One that has at least one route in its routing table that uses an IGW

43
Q

Does VPC peering support edge to edge routing?

A

No