I also hope the other RIRs are reviewing their internal processes to see if they have similar exposures that need to be addressed (no pun intended). Thank you jms On Fri, Dec 12, 2025 at 9:49 PM Brandon Martin via NANOG < nanog@lists.nanog.org> wrote:
On 12/12/25 15:53, William Herrin via NANOG wrote:
464xlat and similar technologies. Basically, ARIN has a set-aside for folks who have IPv6 devices on an IPv6 network that have a need to also talk to IPv4 devices on the Internet via one of the transition technologies. For that specific use case, there's still a pool of unallocated addresses available.
In addition to address translation targets, they can (per policy) be used for other critical functions that require dual-stacking such as DNS servers (both recursive and authoritative noting that there are still a lot of "target" networks that are IPv6-enabled but don't have dual-stack authoritative nameservers) and things like mail servers and potentially even web servers that require "some rando on the Internet" who may not have IPv6 at all to be able to hit them.
The (somewhat unwritten) intent appears to be to allow a newly started entity to still obtain a minimal IPv4 presence so as to facilitate an "IPv6 first" network deployment without having to wait on the waiting list or go to the open market via specified transfer. You can get a 4.10 /24 allocation essentially immediately after having an IPv6 allocation provided you use it for the stated purposes.
A /24 is cramped but largely adequate for this purpose for most newly-started network. If you can justify need for more space such as because your NAT overload ratio is becoming untenable, you can request expansion, and ARIN has policies in place to try to make it so that your expansion space will aggregate with your original space without requiring you to re-number. _______________________________________________ NANOG mailing list
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