Availability and Scalability - ELB

Question 1

What is the purpose of a load balancer?

Answer 1

A load balancer forwards incoming traffic to multiple backend EC2 instances to distribute the load evenly.

Question 2

Why should you use a load balancer in your infrastructure?

Answer 2

It provides a single access point to the application, handles failures, performs health checks on EC2 Instances, provides SSL termination, and scales traffic across instances.

Question 3

What are health checks in a load balancer?

Answer 3

Health checks are used by the load balancer to verify if an EC2 instance is functioning properly. If not, traffic is not routed to that instance.

Question 4

What are the four types of managed load balancers in AWS?

Answer 4

Classic Load Balancer (CLB)
Application Load Balancer (ALB)
Network Load Balancer (NLB)
Gateway Load Balancer (GWLB)

Question 5

What is the Application Load Balancer (ALB) used for?

Answer 5

ALB supports HTTP, HTTPS, and WebSocket protocols, and is used for routing traffic based on URL, content, and host.

Question 6

What is the Network Load Balancer (NLB) used for?

Answer 6

NLB supports TCP, TLS, and UDP protocols and is used for high-performance applications needing low latency and high throughput.

Question 7

What is the Gateway Load Balancer (GWLB) used for?

Answer 7

GWLB operates at the network layer, using IP protocol for routing traffic and integrating with third-party virtual appliances.

Question 8

What is the difference between internal and external load balancers?

Answer 8

Internal load balancers handle private traffic, usually within a VPC.
External load balancers handle public traffic, like web applications.

Question 9

What is the security configuration for a load balancer?

Answer 9

The load balancer’s security group allows traffic from anywhere (0.0.0.0/0) on ports 80 or 443 (HTTP/HTTPS).

Question 10

What is the security configuration for EC2 instances behind a load balancer?

Answer 10

EC2 instances should only allow traffic originating from the load balancer’s security group, enhancing security.

Question 10

What are the advantages of using Elastic Load Balancer (ELB) on AWS?

Answer 10

ELB is managed by AWS, provides high availability, handles scalability and failures, integrates with many AWS services, and is cost-effective compared to managing your own load balancer.

Question 11

What is SSL termination in the context of a load balancer?

Answer 11

SSL termination means that the load balancer decrypts HTTPS traffic, relieving backend instances from handling encryption.

Question 12

What type of traffic does an Application Load Balancer (ALB) handle?

Answer 12

ALB is a Layer 7 load balancer, meaning it handles HTTP/HTTPS
traffic.

Question 13

What is a target group in the context of an Application Load Balancer?

Answer 13

A target group is a set of backend servers or EC2 instances that the load balancer routes traffic to.

Question 14

How does Application Load Balancer route traffic?

Answer 14

ALB routes traffic based on URL paths, host names, query strings, and headers to different target groups.

Question 14

How can ALB route traffic based on URL paths?

Answer 14

For example, traffic to /users can be routed to one target group, while /posts can be routed to another.

Question 15

What can be registered as a target in an ALB target group?

Answer 15

Target groups can include EC2 instances, ECS tasks, Lambda functions, and private IP addresses.

Question 16

What is an example of using multiple target groups with an ALB?

Answer 16

An ALB could route mobile traffic to one target group (e.g., EC2 instances) and desktop traffic to another target group (e.g., on-premises servers).

Question 17

How does ALB differ from the Classic Load Balancer when managing multiple applications?

Answer 17

With ALB, a single load balancer can handle multiple applications, unlike the Classic Load Balancer, which requires a separate load balancer for each application.

Question 18

What type of traffic does a Network Load Balancer (NLB) handle?

Answer 18

NLB is a Layer 4 load balancer, meaning it handles TCP and UDP traffic.

Question 19

What is a key feature of the Network Load Balancer (NLB) in terms of performance?

Answer 19

NLB is known for its ultra-low latency and ability to handle millions of requests per second.

Question 20

What is a unique feature of the Network Load Balancer (NLB) regarding IP addresses?

Answer 20

NLB has one static IP per Availability Zone and allows you to assign Elastic IPs to each AZ.

Question 21

When should you consider using a Network Load Balancer (NLB)?

Answer 21

Consider using NLB when you need extreme performance, need to handle TCP or UDP traffic, or require static IP addresses.

Question 22

What types of target groups can be used with the Network Load Balancer (NLB)?

Answer 22

NLB can route traffic to EC2 instances, private IP addresses, and can even route traffic to an Application Load Balancer (ALB).

Question 23

What types of health checks can Network Load Balancer (NLB) perform?

Answer 23

NLB supports TCP, HTTP, and HTTPS health checks for its target groups.

Question 24

Is Network Load Balancer (NLB) included in the AWS Free Tier?

Answer 24

No, NLB is not included in the AWS Free Tier.

Question 25

What is the purpose of a Gateway Load Balancer (GWLB)?

Answer 25

A Gateway Load Balancer is used to deploy, scale, and manage third-party network appliances (e.g., firewalls, intrusion detection systems) in AWS. It routes all traffic through these appliances for inspection or modification before reaching the application.

Question 26

When would you use a Gateway Load Balancer?

Answer 26

You would use a Gateway Load Balancer if you want to inspect, modify, or secure all network traffic (e.g., firewall, intrusion detection) before sending it to your applications.

Question 27

How does a Gateway Load Balancer work in a network?

Answer 27

The Gateway Load Balancer directs all traffic through a set of third-party virtual appliances for inspection (e.g., firewall or intrusion detection). If the traffic is acceptable, it is sent to the application; otherwise, it is dropped.

Question 28

What is the role of the Gateway Load Balancer in traffic routing?

Answer 28

The GWLB acts as a transparent network gateway, routing all traffic through it. It functions as a load balancer, distributing traffic across a set of virtual appliances (target groups).

Question 29

What does a Gateway Load Balancer operate at?

Answer 29

The GWLB operates at Layer 3 (network layer) of the OSI model, which handles IP packets.

Question 30

What types of targets can be used in the Gateway Load Balancer’s target group?

Answer 30

The target group can consist of EC2 instances (registered by instance ID) or private IP addresses (such as appliances in your data center).

Question 31

What protocol does the Gateway Load Balancer use?

Answer 31

The Gateway Load Balancer uses the GENEVE protocol on port 6081 for communication.

Question 32

What is the advantage of using a Gateway Load Balancer for traffic inspection?

Answer 32

It allows for seamless inspection of all network traffic (e.g., through firewalls or intrusion detection systems) without disrupting the flow to applications, while maintaining a single point of entry and exit for traffic in the VPC.

Question 33

What makes a Gateway Load Balancer different from other AWS load balancers?

Answer 33

Unlike ALB or NLB, which work with application-layer and transport-layer traffic, the GWLB works at the network layer and is specifically designed for routing traffic through third-party network appliances before reaching applications.

Question 34

How does the traffic flow in a Gateway Load Balancer setup?

Answer 34

Traffic first goes through the GWLB, then to a target group of virtual appliances (like firewalls or IDPs) for inspection. If the traffic is approved, it is sent back to the GWLB and then forwarded to the application.