‫So now let's talk about the Network Load Balancer.
‫So it's a Layer four load balancer, and therefore
‫it allows you to deal with TCP and UDP traffic.
‫Okay, this is lower level.
‫Layer seven was HTTP,
‫and layer four is going to be TCP and UDP traffic.
‫So these work for Network load balancer
‫and therefore when in the exam you see UDP,
‫think Network load balancer or even TCP.
‫Okay, also on top of it, the Network load balancer,
‫is really, really high performance
‫and therefore it can handle
‫millions of requests per seconds.
‫And the latency compared to
‫the Application load balancer is lessened.
‫That means you get around a hundred milliseconds
‫versus 400 millisecond for the ALB.
‫Now another specificity of the Network low balancer
‫is that it only has one static IP per availability zones,
‫and you can assign an Elastic IP to each AZ.
‫So this is very helpful when you need to
‫expose your application with a set of static IPs
‫and this can be Elastic IPs.
‫So when the exam you say,
‫"Hey your application can only be accessed
‫within one, two, or three different IPs".
‫Then you need to think about
‫the Network load balancer as an option.
‫So if you see extreme performance, TCP, or UDP,
‫or static IPs think Network load balancer.
‫Now using it is not included in the AWS free tier.
‫So let's have a look at how that works.
‫So it works very similarly to the Application load balancer.
‫We create target groups
‫and then the Network load balancer will redirect to them.
‫So we can use, for example, the TCP traffic,
‫or for example in the backend HTTP,
‫but still in the front end use TCP.
‫So what about the target groups?
‫This is the important parts.
‫So the target groups can be EC2 instances.
‫That means that your Network load balancer
‫can redirect to your EC2 instances
‫and send TCP or UDP traffic to them
‫but you can also register IP addresses,
‫and these IP addresses when they're hardcoded,
‫and they must be hardcoded,
‫they must be private IPs.
‫So why would you do this?
‫Well, you can, of course send the private IP
‫of the EC2 instance that you own,
‫but also you could use the private IP of a server
‫that you have in your own data center.
‫And therefore both of them can be fronted
‫by the same Network load balancer.
‫And it's also possible for you
‫to have a Network load balancer
‫in front of an Application load balancer.
‫So in that case, the NLB is in front of your ALB.
‫So why would you do this?
‫Well, thanks to the Network load balancer,
‫you would get for example, the fixed IP addresses,
‫and then thanks to the Application load balancer,
‫you can get all the rules
‫that you have around handling HTTP type of traffic.
‫So it is a valid combination.
‫Now, one last thing you need to know for the exam,
‫is that the health checks
‫performed by the Network load balancer target groups
‫are support three different kind of protocols.
‫They support the TCP protocol, the HTTP protocol,
‫and the HTTPS protocol.
‫So if your backend application
‫supports the HTTP or HTTPS protocol,
‫then it is definitely possible for you
‫to define a health check on these protocols.
‫Okay, so that's it for the Network load balancer.
‫I hope you liked it.
‫And I will see you in the next lecture.