I know that YOU Broadband provides CGNAT my point is when I entered external IP addressYou Broadband does not provide public IP addresses. Your router's WAN IP assignments is a CG NAT address.
Routing to other IP addresses or domains whether internal or external (as seen when doing trace route) is done in via static or dynamic route tables in the carrier's routers and using one or more Routing Protocols like BGP, OSPF, RIP etc.
According to what I could see in my account, changing the MAC addresses registered there didn't make a difference. Also they restrict changes to once in 30 days.
In my router/firewall I can update static routes through to WAN or within LAN if required on this page.
it use to show some other area pin code but now after changing the mac address now the external ip address which I entered in
showes My mane area pincode under which my locality comes