Intention to enable IPv6 by default in 2017


I’m planning to sometime in 2017 finally making IPv6 (AAAA records) the default for the NTP Pool.

My intention is to allow vendor zones to choose how they want to get AAAA records (or not) for their names, but the default behavior of {0.,1.,2.,3.,} will be to return AAAA records like does today (and have for a few years).

Random Observation
Only one pool for IPv6 in AT, DE, CH
It's 2019 and still no IPv6 by default?

I am not familiar with IPv6, hence the question: if a client computer has IPv6 stack available but does not acquire IPv6 ip from ISP (as most modern computers in Taiwan do), will it be able to send and receive NTP packets to and from pool servers with AAAA addresses?

Image from [Google IPv6 survey] (


To reach IPv6 servers the end machine will need an IPv6 address, or use one of the translation schemes.

If a machine has no IPv6 Internet connectivity the AAAA records will be ignored and the machine will use IPv4.


It wouldn’t (unless you have a tunnel of sorts). The scenario you describe is really the risk for adding IPv6 to all the DNS records (and why I haven’t despite most of the big services doing IPv6).

If your local system thinks it has IPv6 it might ask for the AAAA record, get an IPv6 address and then have it timeout. You can test by configuring your client to use “” (which will offer IPv6 addresses when available).


I occasionally encounter this problem during web browsing, or wgetting, when IPv6 is supported by the DNS but not the network. Eventually after a minute, the correct A record would be tried. Why wasn’t NTP designed to try all the possible A and AAAA records before giving up?


I was not aware that only the 2. entry returned anything when you did query for AAAA… I just checked and yeah if you query any of the 0., 1. or 3. zones for AAAA you just get back SOA…

Curious why was not like this from the get go? I know my ipv6 does get queries… guess the ipv6 traffic will go up if all the zones start returning AAAA when asked…

Great! Nice to seem more an more use of IPv6…

closed #7

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opened #8


Perhaps it’d be worth only enabling IPv6 for zones of countries with decent IPv6 adoption?


Yeah, that might be a reasonable stepping stone until we’re at some tipping point where IPv6 is the default for more users than not.