root@cp1099:/home/bblack# systemctl status gdnsd.service 
● gdnsd.service - gdnsd
   Loaded: loaded (/lib/systemd/system/gdnsd.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-09-12 17:55:37 UTC; 4min 28s ago
     Docs: man:gdnsd
 Main PID: 36748 (gdnsd)
    Tasks: 66 (limit: 7372)
   CGroup: /system.slice/gdnsd.service
           └─36748 /usr/sbin/gdnsd -c /etc/gdnsd -Tl start
[...]

root@cp1099:/home/bblack# gdnsdctl replace
info: Existing daemon: version 2.99.6 running at pid 36748
info: Server at pid 36748 exited after stop command
info: Replacement daemon: version 2.99.6 running at pid 38167
root@cp1099:/home/bblack# echo $?
0
root@cp1099:/home/bblack# systemctl status gdnsd.service 
● gdnsd.service - gdnsd
   Loaded: loaded (/lib/systemd/system/gdnsd.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-09-12 17:55:37 UTC; 4min 41s ago
     Docs: man:gdnsd
 Main PID: 38167 (gdnsd)
    Tasks: 66 (limit: 7372)
   CGroup: /system.slice/gdnsd.service
           └─38167 /usr/sbin/gdnsd -c /etc/gdnsd -Tl start

Sep 12 18:00:12 cp1099 gdnsd[38167]: state of '10.64.32.24/discovery-state-failoid' initialized to UP/10
Sep 12 18:00:12 cp1099 gdnsd[38167]: state of '10.192.16.25/discovery-state-failoid' initialized to UP/10
Sep 12 18:00:12 cp1099 gdnsd[38167]: Initial round of monitoring complete
Sep 12 18:00:12 cp1099 gdnsd[38167]: admin_state: state file '/var/lib/gdnsd/admin_state' does not yet exist at startup
Sep 12 18:00:12 cp1099 gdnsd[38167]: Executing actual takeover of v2.99.6 running at pid 36748
Sep 12 18:00:12 cp1099 gdnsd[38167]: Takeover request accepted
Sep 12 18:00:12 cp1099 gdnsd[38167]: Socket takeover: got 64 DNS sockets
Sep 12 18:00:12 cp1099 gdnsd[38167]: DNS listeners started
Sep 12 18:00:12 cp1099 gdnsd[38167]: Stop command to server pid 36748 succeeded
Sep 12 18:00:12 cp1099 gdnsd[38167]: Server at pid 36748 exited after stop command