These are my 3 servers.

Load Balancer-192.168.1.72
Server-01-192.168.1.79
Server-02-192.168.1.80

In Load Balancer Server, I've configured these things in /etc/nginx/conf.d/load-balancer.conf

upstream backend{
  server 192.168.1.79:80;
  server 192.168.1.80:80;
}

server {
  listen 80;
  server_name localhost;
  
  location / {
  proxy_pass http://backend;
  }
}

In server-01, I've configured this thing in /usr/share/nginx/html/index.html

cat index.html
This is server-01

In server-02, I've configured this thing in /usr/share/nginx/html/index.html

cat index.html
This is server-02

The problem

The configuration is successful. But when I curl localhost:80 , I am getting empty response(which is the content at /usr/share/nginx/html for load-balancer.)

What's the issue here and how can I resolve it. I suspect it's something related to DNS. But I'm not aware how I fix this issue?

I added

192.168.1.72 localhost

to /etc/hosts of load-balancer server.

How do I solve this issue?