Enable IPv6 for openwrt.pool.ntp.org

Feature Requests
1

I just noticed, that time and date is not updated on nodes in my IPv6-only network.

Out of 0–3, only 2.openwrt.pool.ntp.org has AAAA records enabled. If those servers are maintained by members of the OpenWRT project, I would be happy if they could enable IPv6 for all of them.

2.openwrt.pool.ntp.org.	81	IN	AAAA	2a01:4f8:110:12d5::2
2.openwrt.pool.ntp.org.	81	IN	AAAA	2a01:4f8:c2c:3d20::1
2.openwrt.pool.ntp.org.	81	IN	AAAA	2a01:238:427e:1e00:f21d:ee49:2a64:3256
2.openwrt.pool.ntp.org.	81	IN	AAAA	2a01:4f8:200:3296::2
1 Like
2

They're not - they'remaintained just as any other server in the pool:

See: https://www.pool.ntp.org/en/vendors.html#vendor-zone

I would suggest using IPv6 IP or a server with a known AAAA record.

2 Likes
3

That is a documented decision by ntp.org, only the '2.*.ntp.org' servers are IPv6 enabled (sorry, can't find my reference right now, but I too want all my ntp servers to be IPv6 capable, and I've dug into this).

Here's a list of v6 capable servers I've collected over the years. I occasionally ping them to get the ones with lowest RTT, then use the four that are 'closest' to me in that regard. Those Hurricane Electric (he.net) ones in San Jose and Fremont California are always very fast for me, but that's because of geographic proximity. Cloudflare and Google are almost always good, too.

    2.pool.ntp.org
    2.us.pool.ntp.org
    clock.fmt.he.net
    clock.sjc.he.net
    ntp.he.net
    time-d-wwv.nist.gov
    time-e-wwv.nist.gov
    time.cloudflare.com
    time.google.com
3 Likes
4

Here’s an old reference:

2 Likes
5

Are you guys using the default included busybox ntpd or swapped it out? Because mine seems to have problems with IPv6. Found an old auto closed issue on it https://github.com/openwrt/openwrt/issues/8807

root@OpenWrt:~# ntpd -
BusyBox v1.37.0 (2025-08-25 17:52:43 UTC) multi-call binary.

root@OpenWrt:~# ntpd -dwqp 2.openwrt.pool.ntp.org
ntpd: '2.openwrt.pool.ntp.org' is 2001:9b1:9bd0::bb
ntpd: sending query to 2001:9b1:9bd0::bb
Alarm clock

root@OpenWrt:~# ping 2.openwrt.pool.ntp.org
PING 2.openwrt.pool.ntp.org (2a05:f480:2000:2c23:5400:5ff:fe3b:6d64): 56 data bytes
64 bytes from 2a05:f480:2000:2c23:5400:5ff:fe3b:6d64: seq=0 ttl=50 time=10.878 ms
64 bytes from 2a05:f480:2000:2c23:5400:5ff:fe3b:6d64: seq=1 ttl=50 time=10.612 ms
64 bytes from 2a05:f480:2000:2c23:5400:5ff:fe3b:6d64: seq=2 ttl=50 time=10.573 ms
6

root@router:~# ntpd -dwqp 2.openwrt.pool.ntp.org
ntpd: '2.openwrt.pool.ntp.org' is 2a01:4f9:c011:a343:123:123:123:123
ntpd: sending query to 2a01:4f9:c011:a343:123:123:123:123
ntpd: reply from 2a01:4f9:c011:a343:123:123:123:123: offset:+0.002437 delay:0.070106 status:0x24 strat:2 refid:0xa98f47f2 rootdelay:0.009110 reach:0x01

3 Likes
7

Forgot to add that I’m running OpenWrt SNAPSHOT, r30886-6fbf6d0cfd

What version of ntp are you using and what OpenWrt version?

ntpd -

ntpd -dwqp 2a01:4f9:c011:a343:123:123:123:123
ntpd: sending query to 2a01:4f9:c011:a343:123:123:123:123
Alarm clock
8

OpenWrt 24.10.2 r28739-d9340319c6 and BusyBox v1.36.1 (2025-06-23 20:40:36 UTC) multi-call binary.

1 Like
9

Got the same error from 24.10.2 but the same provider and router T56, though different location

10

2.pool.ntp.org is the only one always handing out some ipv6 address even not having ipv6 connectivity. It is documented in their forums.

1 Like
11

Both time.google.com and time.cloudflare.com support IPv6.

12

My ntp server list was culled to included only those that support IPv6:

    clock.fmt.he.net
    clock.sjc.he.net
    ntp.he.net
    time-d-wwv.nist.gov
    time-e-wwv.nist.gov
    time.cloudflare.com
    time.google.com

I particularly like those first two Hurricane Electric ones, as they have the lowest RTT for me; I suspect I have a straight shot up the coast to them on some link with very low hop count... (That being said, I don't actually use any of them except to bootstrap my local GPS-based ntp server.)

13

Google says to stay out of theirs.

14

Does it not work? I actually never tried it in production. I just know that many devices use it de-facto.

15

I believe you're referring to the recommendation that you not mix servers with theirs because they do something called "Leap Smear". See:

1 Like
16

Yes this.

Or, use only googles ntp or any other where you know they smear leap seconds and such.

1 Like
17

This topic was automatically closed 10 days after the last reply. New replies are no longer allowed.