2001:500:2d::d - d.root-servers.net behavior

[Thomas Mieslinger]

Source IP 2001:8d8:5c0:452:212:227:19:3 can not query 2001:500:2d::d.
Source IP 2001:8d8:5c0:452:212:227:19:2 can query 2001:500:2d::d.

I analyzed the outgoing queries of my recursors 
2001:8d8:5c0:452:212:227:19:2 and 2001:8d8:5c0:452:212:227:19:3

I see about 10 req per _minute_ towards 2001:500:2d::d

Couldn't reach anyone at pch.

Please contact me via pm if you can/want to help with this matter.

Source IP 2001:8d8:5c0:452:212:227:19:3 can not query 2001:500:2d::d. 
Not over udp, not over tcp
mtr looks like this
> HOST: rec-int-fr-nbz-kw02.server. Loss%   Snt   Last   Avg  Best  Wrst StDev
>   1.|-- irb-381.gw-dists1-a.kw.nb  0.0%     1    0.4   0.4   0.4   0.4   0.0
>   2.|-- lo-0.rc-b.kw.nbz.fr.net.i  0.0%     1    0.7   0.7   0.7   0.7   0.0
>   3.|-- lo-0.rc-b.bs.kae.de.net.i  0.0%     1    3.0   3.0   3.0   3.0   0.0
>   4.|-- lo-0.bb-b.fr7.fra.de.net.  0.0%     1    3.4   3.4   3.4   3.4   0.0
>   5.|-- ionos.bcix.de              0.0%     1   12.1  12.1  12.1  12.1   0.0
>   6.|-- ???                       100.0     1    0.0   0.0   0.0   0.0   0.0
>   7.|-- ???                       100.0     1    0.0   0.0   0.0   0.0   0.0
>   8.|-- as42.berlin.megaport.com   0.0%     1   12.1  12.1  12.1  12.1   0.0
>   9.|-- d.root-servers.net         0.0%     1   12.3  12.3  12.3  12.3   0.0


Source IP 2001:8d8:5c0:452:212:227:19:2 can query 2001:500:2d::d.
> HOST: rec-int-fr-nbz-kw01.server. Loss%   Snt   Last   Avg  Best  Wrst StDev
>   1.|-- irb-381.gw-dists1-a.kw.nb  0.0%     1    0.3   0.3   0.3   0.3   0.0
>   2.|-- lo-0.rc-b.kw.nbz.fr.net.i  0.0%     1    0.6   0.6   0.6   0.6   0.0
>   3.|-- lo-0.rc-b.bs.kae.de.net.i  0.0%     1    2.9   2.9   2.9   2.9   0.0
>   4.|-- lo-0.bb-b.fr7.fra.de.net.  0.0%     1    3.8   3.8   3.8   3.8   0.0
>   5.|-- ionos.bcix.de              0.0%     1   12.3  12.3  12.3  12.3   0.0
>   6.|-- ???                       100.0     1    0.0   0.0   0.0   0.0   0.0
>   7.|-- d.root-servers.net         0.0%     1   12.1  12.1  12.1  12.1   0.0