Correct answer - "Look into the X-Forwarded-For header in the backend" : The X-Forwarded-For
request header helps you identify the IP address of a client when you use an HTTP or HTTPS load
balancer. Because load balancers intercept traffic between clients and servers, your server
access logs contain only the IP address of the load balancer. To see the IP address of the
client, use the X-Forwarded-For request header. Elastic Load Balancing stores the IP address of
the client in the X-Forwarded-For request header and passes the header to your server.
Incorrect:
"Modify the front-end of the website so that the users send their IP in the requests" - When a
user makes a request the IP address is sent with the request to the server and the load balancer
intercepts it. There is no need to modify the application
"Look into the X-Forwarded-Proto header in the backend" - The X-Forwarded-Proto request header
helps you identify the protocol (HTTP or HTTPS) that a client used to connect to your load
balancer
"Look into the client's cookie" - For this we would need to modify the client side logic and
server side logic, which would not be efficient