ubuntu@icarus-maas:~⟫ date
Wed Oct  9 10:45:01 UTC 2019
ubuntu@icarus-maas:~⟫ ps axuw |grep bind
bind        404  4.3  0.1 3703664 326056 ?      Ssl  Sep30 550:09 /usr/sbin/named -f -u bind
maas      15192  0.0  0.0 174476  5292 ?        Sl   06:18   0:00 rndc -c /etc/bind/maas/rndc.conf.maas reload

RNDC socket appears to not be serviced by BIND

All BIND threads stuck/quiet.

ubuntu@icarus-maas:~⟫ dpkg -l |grep bind9
ii  bind9                            1:9.10.3.dfsg.P4-8ubuntu1.14               amd64        Internet Domain Name Server

bind9 (1:9.10.3.dfsg.P4-8ubuntu1.15) xenial; urgency=medium

  * d/p/ubuntu//lp-1833400*: fix race on shutdown (LP: #1833400)
  * d/p/fix-shutdown-race.diff: dig/host/nslookup could crash when interrupted
    close to a query timeout (LP: #1797926)

This does not appear to be relevant for the problem at hand.

ubuntu@icarus-maas:~⟫ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.6 LTS
Release:        16.04
Codename:       xenial

Perhaps we should upgrade to Bionic?

ubuntu@icarus-maas:~⟫ sudo strace -ffp 404
sudo: unable to resolve host icarus-maas
strace: Process 404 attached with 51 threads
[pid   458] epoll_wait(7,  <unfinished ...>
[pid   457] restart_syscall(<... resuming interrupted restart_syscall ...> <unfinished ...>
[pid   456] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   455] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   454] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   453] futex(0x7f88afcf90d4, FUTEX_WAIT_PRIVATE, 17981, NULL <unfinished ...>
[pid   452] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   451] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   450] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   449] futex(0x7f88004f25c8, FUTEX_WAIT_PRIVATE, 2, NULL <unfinished ...>
[pid   448] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   447] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   446] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   445] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   444] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   443] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   442] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   441] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   440] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   439] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   438] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   437] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   436] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   435] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   434] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   433] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   432] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   431] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   430] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   429] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   428] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   427] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   426] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   425] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   424] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   423] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   422] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   421] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   420] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   419] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   418] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   417] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   416] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   415] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   414] futex(0x7f88004f11b8, FUTEX_WAIT_PRIVATE, 2, NULL <unfinished ...>
[pid   413] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   412] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   411] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   409] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   410] futex(0x7f88afcf90a4, FUTEX_WAIT_PRIVATE, 92336049, NULL <unfinished ...>
[pid   404] rt_sigsuspend([], 8