The reason not to convert all systems at the same time is simple: Many older PCs, network switches, routers, print servers, and other network devices may not . While a server could run both IPv4 and IPv6, and permit both types of connected devices to talk to one another, this arrangement introduces additional complexity and can contribute to the load on the server. In addition, network administrators will need to switch the setup over, a process that can take at least a few minutes for each device on the network.

Many organizations may not even need to switch at all until their ISP does. for many years to come, and your ISP will translate automatically for you if your network is still using IPv4. If you want to use an IPv6 address for your network, or if your ISP notifies you that it is converting and that you'll need to have an IPv6 address, the conversion process happens in two steps: First, you'll need to get a new address, and second, you'll need a router (or firewall/router) that supports IPv6.

The external IP address your network will have is assigned by your ISP and is used by any outside system sending data to your network. You'll need to coordinate with your ISP to obtain this address. The address then needs to be associated with the names of your e-mail, Web, and other servers, using the domain name service (DNS). Registering an IPv6 address for a domain name can still be complex, and some providers may not have a system in place for that yet.

If your servers are hosted by a third-party provider such as GoDaddy or Google, you shouldn't need to worry about IPv6 and DNS; your service provider should take care of the conversion for you.