The document explains the types of load balancers in AWS, including Application Load Balancer, Network Load Balancer, and Classic Load Balancer, each defined by their operational layers and functionality. It also highlights potential load balancer errors, such as error 504, indicating communication issues with EC2 instances. The role of the x-forwarded-for-header in identifying user IP addresses is discussed as well, providing insight into user engagement.

1. What is Load Balancer in AWS
and Types of Load Balancers

2. Load Balancer is a virtual machine or equipment that balances your web
application load that might be Http or Https visitors which you are getting
in.
1. Application Load Balancer:
• An Amazon Web Services (AWS) launched a fresh load balancer called an
Application load balancer (ALB) on August 11, 2016.
• It is used to direct user site visitors to the public AWS cloud.
• It identifies the incoming traffic and forwards it to the proper resources.

3. • It is managed at Layer 7 of the OSI Model.
• It is quality perfect for the load balancing of HTTP and HTTPs site visitors.
• Application load balancers are intelligent, sending precise requests to
particular internet servers.
2. Network Load Balancer:
• It is operated at Layer four of the OSI model.
• It makes routing choices at the transport layer (TCP/SSL), and it can
handle thousands and thousands of requests per second.
• When a load balancer receives a connection, it then selects a goal from
the target organization by using a flow hash routing algorithm.

4. • It opens the TCP connection to the chosen target of the port and forwards
the request without editing the headers.
• It is exceptionally desirable for load balancing the TCP site visitors when
excessive performance is required.
3. Classic Load Balancer:
• It is operated at Layer four of the OSI model.
• It routes the site visitors between clients and backend servers primarily
based on IP address.
• Classic Load balancers are inheritance Elastic load balancers.

5. • It can also be used for load balancing the HTTP or HTTPs traffic and use
layer 7-unique features, along with X-forwarded and sticky sessions.
• You can also use the Layer four load balancing for programs that depend
purely on the TCP protocol.
Load Balancer Errors:
Classic Load Balancer:
• If you get an error 504, that is a gateway timeout error. A Load balancer
continues to be available, but it has a hassle in communicating with the
EC2 instance.
• If your application stops reacting, the ELB (Classic Load Balancer)
responds with a 504 error.

6. • This way that the application is having issues and it can be either at the
web server layer or the Database layer. In order to troubleshoot where
the utility is failing, and scale it up or out wherein possible.
X-Forwarded-For-Header:
The X-Forwarded-For-Header is used to decide the IP address of a purchaser
when you use a classic load balancer.
Working of X-Forwarded-For-Header:
• A consumer is on the Ipv4 address, i.e., 124.12.3.23.
• A user is sending a request to the classic load balancer which in turn
folded the request into an EC2 example.
• An EC2 example goes to use the private address, i.e., 10.0.0.23 and that is
the best address which is seen with the aid of an EC2 example.

7. • An EC2 instance is capturing the simplest private address as a Classic Load
balancer that encompasses the Public IP address. The public address is
needed because it affords valuable information such as "who is the usage
of your website".
• An EC2 example receives the Ipv4 address in the form of X-Forwarded-For
request Header from the Classic load balancer.

8. For More Information on AWS Click Below Link
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