A note on Rackspace: we see about 2–3% of the VMs we allocate come with only an IPv4 address. We have no idea why — we suspect it's a bug on Rackspace's side (we allocate everything automatically, through the same code path, so it isn't us!).
We currently only use the IPv4 address (I know, I know!), but it does present a bit of a problem when/if we decide to move.
I work at Rackspace and I'd love to get our product engineers involved and review this issue for you. Would it be possible for you to email your account number and any pertinent server information (hostname/IP address/etc) to help@rackspace.com so that we can investigate?
Thanks!
Andy Pape
Social Media Support
@Racker_Andy
We currently only use the IPv4 address (I know, I know!), but it does present a bit of a problem when/if we decide to move.