To allow access to you web site, a service convert IPv4 access to IPv6 and call your service into IPv6.
Then You will show the IPv6 of this service and not the real IPv4 used for IPv4 connections.
Take care of the HTTP headers:
From:
PS: have similar mecanism for DNS, SNMP (protocol on fixed port), for more security the port of SSH/SFTP, POP3, IMAP is randomised