They buy them;
Just as Amazon (and other big ones) do.
Have you ever compared the prices of these VPS to IPv6-only VPS and wondered why IPv6-only ones are so much cheaper?
By definition there are only ~4 billion IPv4 addresses available. No matter how fair you distribute them; that is simply not sufficient for todays -let alone future- demand.
This topic is temporarily closed for at least 4 hours due to a large number of community flags.
This topic was automatically opened after 22 days.
The client can always select to use “server -4 *.pool.ntp.org” to get IPv4 only, or “server -6 *.pool.ntp.org” to get IPv6 only. There is no need to break the geographical structure by adding a special IPv6 subdomain.
True, but still i’m looking forward to have ipv6 enabled across the board, instead of relying on client config (which might not always be possible on some very simple IoT clients).
I suspect i might have to reduce the server bandwidth setting when a flood of ipv4 clients will be routed to my ipv6 servers 
On client-side I use a self-hosted instance of AdGuard Home (Works similarly to Pi-hole but is better in every way) to redirect IPv6 DNS lookup requests to NTP’s 2.(…) IPv6 addresses. For the main pool•ntp•org domain, I use:
|pool.ntp.org|$dnstype=AAAA,dnsrewrite=2.pool.ntp.org
|0.pool.ntp.org|$dnstype=AAAA,dnsrewrite=2.pool.ntp.org
|1.pool.ntp.org|$dnstype=AAAA,dnsrewrite=2.pool.ntp.org
|3.pool.ntp.org|$dnstype=AAAA,dnsrewrite=2.pool.ntp.org
This workaround is something that most client users out there would be unlikely to set up successfully, however.
Interesting observation:
Ubuntu is planning to replace systemd-timesyncd with Chrony starting with release 25.10.
It will come pre-configured with their own NTS-enabled servers, which also happen to support IPv6. In the default configuration, the traditional NTP Pool servers are still present, but commented out, so they remain available for those who prefer them:
This is what I wrote some four years ago. I’d still suggest an approach similar to the above.
I would think that any possible concerns regarding IPv6 addresses have faded away by now. For example devices that only supported IPv4 are most probably out of support by now, replaced by newer devices that support IPv6. Google’s global statistics tell me that IPv6 adoption has increased from around 35% to 46% in these four years.
My biggest concern with IPv4 is CGNAT. There are regional differences in how CGNAT gets implemented, but a typical scenario might be that a single IPv4 address is shared between multiple customers, but each customer gets their own IPv6 address (or a network). Even my parents have this kind of configuration at home with their home fibre. Please also note that CGNAT usage may differ between regions.
CGNAT causes problems for NTP server operators trying to configure rate limiting for their servers. Some IPv4 address might be in use by one person and another IPv4 address by 100 persons. Good luck coming up with a configuration that is suitable for both. With IPv6 each user would get their own IPv6 address which could be rate-limited independently.
It’s not a matter of “if” but “when”. The NTP pool must get full IPv6 support at some point and I’d prefer to have it soon.
Of course I agree.
It’s pretty ironic when you think about it. Many of us have been trying to explain why adding more AAAA records to the pool is most likely not going to cause issues, yet I see very little evidence of the opposite.
People are configuring time.nist.gov, time.google.com, time.cloudflare.com, time.apple.com, time.facebook.com, ntp.ubuntu.com, time.aws.com, ntp.se, ntp.ripe.net, ntp.time.nl, 2.pool.ntp.org, and many others - all IPv6-enabled - without any problems whatsoever.
I have added a number of IPv6-only servers to the pool (because IPv6-only VMs are really cheap), and it is disappointing that they are not leveraged to their full potential solely because AAAA records are missing from the DNS.
Is it known who is responsible for that and why those people are
refusing to add them?