Dual stack is a migration concept for the transition from the IPv4 protocol to the IPv6 protocol, in which both IP protocols work in parallel and are supported by all network nodes.
The migration is reflected in the transition from one IP protocol to the other, as well as in the access of both protocols to one and the same website, despite different IP addresses. If a website is to be accessed with IPv4 and with IPv6, then two resource records( RR) are set in the zone file. The one for the IPv4 address as A record and the one for the IPv6 address as AAAA record. On the web server, the IPv4 address and the IPv6 address for the website are also stored.
Migration from IPv4 to IPv6 via dual stack increases the administration effort because the IP addresses of both IP protocols and access control lists have to be edited.