Step 1: Launch 3 Servers

1st - Nginx Reverse Proxy

2nd - Application Server

3rd - Authentication Server

Step 2: Install Nginx using RPM Method

yum -y install wget
wget https://nginx.org/packages/centos/8/x86_64/RPMS/nginx-1.20.1-1.el8.ngx.x86_64.rpm
yum -y install nginx-1.20.1-1.el8.ngx.x86_64.rpm
systemctl start nginx

Step 3: Installing net-tools

yum -y install net-tools
ifconfig

Step 4: Adding contents to html file

Admin Server:

cd /usr/share/nginx/html
echo "This is application server backend" > index.html

Auth Server:

cd /usr/share/nginx/html
mkdir admin
echo "This is auth server file under admin" > index.html

Disable SELinux:

getenforce
setenforce 0

Final Configuration:

cd /etc/nginx/conf.d
nano proxy.conf

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_pass http://10.139.0.3;
    }

    location /admin {
        proxy_pass http://139.59.11.125;
      }
}

nginx -t
systemctl restart nginx