Whenever I see the word Operation, especially Trifling Operation, I at once write off the patient as dead.
George Bernard Shaw
In this chapter, we deal with the issues involved in actually operating your network once you have it installed. We'll look at how to configure the necessary infrastructure services and network glue such as DNS and firewalls. Finally, we'll consider some examples of transition and interoperability—how to live peacefully with IPv6 and IPv4 into the foreseeable future.
DNS is the first service that needs to be configured while you are working with IPv6, since just about every network service of consequence involves converting hostnames to IP addresses and back again. (It's even more crucial than in IPv4, since the addresses are so much longer to type and harder to remember.)
When you add IPv6 addresses to your existing DNS records, it is worth emphasizing that you are adding them. Your usual IPv4 addresses remain in place and applications that know nothing about IPv6 will continue to use IPv4. Even applications that understand IPv6 but are not yet connected to the IPv6 Internet should work too, since they should "fall back" to the IPv4 addresses once it becomes apparent that IPv6 isn't connected.
A second important thing to keep in mind is your DNS server doesn't have to speak IPv6 itself to answer a request for an IPv6 address: any request, irrespective of whether it's for an IPv4 or IPv6 address, can itself be made over IPv4 or IPv6. ...