Infra URLs to be whitelisted

For our application we need to whitelist the Infura URLs in our firewall. We have whitelisted the following URLs to get a connectivity to Ropsten:
https://ropsten.infura.io/*
wss://ropsten.infura.io/*

However, the firewall still refuses the connection. We suppose that there are some hidden redirects or responses. A nslookup ropsten.infura.io revealed redirects to a AWS URL.

nslookup ropsten.infura.io
Server:             127.0.0.53
Address:      127.0.0.53#53

    Non-authoritative answer:
    ropsten.infura.io   canonical name = monorepo-production-edge-alb-985829473.us-east-1.elb.amazonaws.com.
    Name:  monorepo-production-edge-alb-985829473.us-east-1.elb.amazonaws.com
    Address: 52.3.78.131
    Name:  monorepo-production-edge-alb-985829473.us-east-1.elb.amazonaws.com
    Address: 52.1.99.4
    Name:  monorepo-production-edge-alb-985829473.us-east-1.elb.amazonaws.com
    Address: 35.169.193.102
    Name:  monorepo-production-edge-alb-985829473.us-east-1.elb.amazonaws.com
    Address: 34.236.103.137

Can anyone tell me if the AWS URL is constant or how we could proceed to get Infura whitelisted on our firewall?

This is not a redirect it is a DNS CNAME record. Does your firewall appliance require explicit A records to be whitelisted?