Actually, IPv6 addresses cannot be longer than 32 digits. Some practical ones can be rather short, usually just slightly longer than a comparable IPv4 address.

Actually, IPv6 addresses cannot be longer than 32 digits. Some practical ones can be rather short, usually just slightly longer than a comparable IPv4 address. Such addresses would be used where remembering/ recognizing the exact IPv4 or IPv6 is relevant, such as the DNS servers or the network hand-off IP/ floating-IP on a firewall cluster or something like that that are used for the bring-up of other services. I have done my fare share of devops/ IT/ administration and engineering of largish enterprise and campus networks. You would be surprised how much hardware and software doesn't support IPv6 properly. Sometimes it is the basic things, sometimes the more advanced stuff but that just means it takes a second or multiple days to find out. The problem is, it just is a similar but different protocol so you have to be quite diligent and check everything you need for the device/ service to work. People do all kinds of stuff on underlay and overlay networks. E.g. some Dell VxRail hyper-converged appliances use IPv6 for the management network https://i.dell.com/sites/csdocuments/Shared-Content_data-Sheets_Documents/en/dellemc-vxrail-networking-guidelines.pdf https://i.dell.com/sites/csdocuments/Shared-Content_data-She.... This is basically just link-local addresses for L2 reachability if I remember correctly but they could've gone with IPv4 there as well. It certainly would be more common for enterprise appliances to not rely on IPv6 for anything even when it shouldn't make a difference whether you do.