[Samba] After a power outage Samba DNS is no longer working properly

[Patrick Goetz]

   OS: Ubuntu 20.04.3
   Samba version: 4.15.2 from Louis' repo

We suffered a power outage after which Samba DNS resolution no longer 
works and I can't figure out why.  The domain controller continues to be 
aware of its client machines:

root at samba-dc:~# samba-tool dns query samba-dc ea.my_org.org ea124 A -U 
Administrator
Password for [EA\Administrator]:
   Name=, Records=1, Children=0
     A: 172.18.90.124 (flags=f0, serial=110, ttl=1200)


root at samba-dc:~# samba-tool dns query samba-dc 90.18.172.in-addr.arpa 
124 PTR -U Administrator
Password for [EA\Administrator]:
   Name=, Records=1, Children=0
     PTR: EA124.ea.my_org.org (flags=f0, serial=7, ttl=900)

However, on the Windows 10 clients (specifically ea124)

   net use G: \\data2\share

gives a characteristically cryptic Microsoft error message: Error 53
which turns out to mean it can't resolve the host name.  If I substitute 
the share server's IP address:

   net use G: \\127.18.90.30\share

then the mount executes as one would expect.

The Wiki page here: https://wiki.samba.org/index.php/DNS_Administration

is very sparse on details of how one would go about debugging or 
repairing this issue.  I seem to recall people running into this on much 
larger networks than mine, but googling and searching the list didn't 
bring up any useful information.

Anyone have any ideas?