Hi, everyone, and welcome back.
Now in today's video, we are going to discuss about the availability zones and the Elbe nodes.
Now, one important thing that you always have to verify is that whenever you create a new load balancer,
that load balancer must be associated with the right set of availability zones where your ESI two instances
would be running.
So when you enable a availability zone for a load balancer, your LP creates a load balancer node.
In that availability zone, for example, let's say that there are two availability zones in this diagram.
Easy one and easy to and in each ESI, there is a single ESI two instance that is running.
So whenever you create an LP, it is important that you register this LP with both of these availability
zones.
And once you register this, a LP node is created and through this specific interface the traffic goes
to the respective ESI two instances that are part of that availability zones.
Now one important thing to note is that if you register a target in an availability zone, but that
availability zone is not enabled at the LP level, these registered targets will not receive that traffic.
Very important part to remember specifically during troubleshooting if your traffic is not reaching
the AC to ATL.
So let's do one thing.
Let's go ahead and look into it practically.
Now for today's video.
I have four ESI, two instances that are running.
Let's look into the instance.
Number one, to see in which availability zone it is associated with the AC two instance.
Number one is associated with the availability zone of one be the ESI two instance.
Number two, again, it's associated with one, be the new server.
Number one is associated with one C and the new server number two is also associated with one C.
So from here we can identify that all of the instances are either associated with the availability zone
of one B and one C.
Now, I also have a load balancer that is available.
And if you look into this load balancer in this availability zone over here, you have one B and you
have one eight.
And also let's look into the target groups.
So there is one target group.
And in this target group you have four ESI, two instances that are available.
Now, one thing that you will see is that under the health status of new server one and the new server
two, it is stating as unused.
So if I'll quickly open up the web server IP address here, let's open this up within here it is stating
website zero three and let's open up the new server two IP address as well and I'll add it in the browser.
This time it is showing website zero four.
So the web server is perfectly working in these instances, but it is still been unused primarily because
it states that the target is in an availability zone that is not enabled by the load balancer.
So since this too is the two instances are in the availability zone of one C, you have to explicitly
enable it.
So in this availability zone.
You have to explicitly add this one C over here, otherwise the traffic will not reach these instances.
So let's go ahead and try to copy that DNS name of the load balancer.
Let me add it in the browser.
It is going to website zero to, if I refresh it now, went to website zero one if I refresh again website
zero two now website zero one grid.
So I hope that this you understood on why the traffic although the AC two instances are registered in
the target group but the traffic is not reaching them.
Now if I go ahead and add the availability zone number C within here, let's save this.
And this time you see the traffic is reaching the website zero three and website zero four.
So your website zero one, your website zero three, you have websites zero four and so on.
So these are the newer, easy two instances in the availability zone of one.
See, now even in the target group here, you see the status changed from unused to healthy grid.
So this will conclude today's video.