Introduction to Elastic Load Balancing

Introduction and Aim
The purpose of this lab is to gain an understanding of the Amazon Elastic Load Balancer. QwikLabs describes the Amzon Elastic Load Balancer (ELB) as a ‘service that automatically distributes incoming application traffic across multiple EC2 instances.’ This can increase the fault tolerance in applications as the ELB service responds to incoming traffic with the required load balancing capacity. The ELB service can be provided for within a single availability zone, or throughout many zones. This service can also be used in a VPC.



  • Logging into the Amazon Management Console
  • Creating an Elastic Load Balancer
  • Adding Instances to an Elastic Load Balancer


Logging into the Amazon Management console
When using AWS, I log into the console through my administrator account rather than my root account. This is a security measure as my root account has access to the financial aspect of AWS. If I were intending to use AWS in  a business scheme or for sensitive information, I would have more users, each with access corresponding to the level of security required.
In order to reduce latency, my AWS account is set in the Sydney region. Although not every service is available at the Sydney zone, I’m currently only working with the basics of what AWS can provide, so I haven’t yet come across any availability issues.


Creating an Elastic Load Balancer
ELBs are located within the EC2 service. For this lab, I choose a classic load balancer which I’ve called ‘free-lab-load-balancer’.
Classic LB
The security group assigned to the ELB is a new one called ELB-SG1. The lab script has a preset one, but as the lab script is being used only as a guideline, then I needed to use an existing one or make a new one.
InkedAssign SG (NEW) New SG_LI
The Type is an AWS preset configuration, so I’m keeping it as is.

The next step in the Load Balance launch is the ‘Configure Security Settings’,  in which nothing is changed, so I just move onto the ‘Configure Health Check’ screen. When I did this, a warning screen appeared:
Config Sec Settings Warning
This warning is something to be heeded for future professional use, but not for this lab.
The lab script asks for the following values:
Response Timeout: 2 seconds
Health Check Interval: 6 seconds
Unhealthy Threshold: 2
Healthy Threshold: 2
Config Health Check

The next step is to add EC2 Instances, I chose two arbitrary instances that were displayed in my instance option list.
Adding EC2 Instances

As Tags are not a part of this exercise, I move on to the final step of reviewing all the load balance specifications.
ELB Review
After checking that everything was according to the script, the load balance can be created.


Once the load balance is created, I can click on the ‘Instance’ tab alongside the ‘Description’ tab near the bottom of the screen. ELB has alt-text that is displayed over the ‘i’ picture next to the instances. The alt-text reports on the status of the instances in relation to the load balance.
Instances Within the ELB
In the ‘Description’ tab, the DNS field name contains a hyperlink that when copied into the browser window, directs to the load balance page. QwikLabs states that ‘While it all looks the same on the front end, as you refresh the page, on the back end your requests are being load balanced between your two running instances.’

The DNS link didn’t work for me, and instead just showed a blank screen. Upon further inspection with the Firefox developer tool, the network was reporting an Error 503, which is a back end server problem.
Back End Server Unavailable

I considered that perhaps I had made a mistake during the load balance launch process, so I created another load balance, taking a look at a classmate’s blog for assistance and rigorously looking over the lab script again.

The DNS link result this time was: Server not found. Using the developer tool, I was able to see that it wasn’t the same problem as my previous load balance as my previous load balance, which implied that it wasn’t a back-end server issue anymore.
Network Display for LB 2
DNS Resolution
Unfortunately, I still didn’t know what the problem seemed to be, or why the problem was no longer a back end issue.


This was an interesting lab in the application of a multi-instance service such as the Amazon Elastic Load Balance. I would like to know why the DNS link failed, and I’m not confident that I could determine that on my own. Having a trained person explain the methods and reasons behind the specifications of the launching of an ELB, may be a beneficial method in helping me understand how to correctly implement the ELB service.


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