I was having a bit of difficult of turning Avahi-Daemon which is also called mDNS since I do not need the Service. When I use the command

# systemctl status avahi-daemon
● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
   Loaded: loaded (/usr/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2023-08-28 08:46:26 +08; 14h ago
 Main PID: 36457 (avahi-daemon)
   Status: "avahi-daemon 0.6.31 starting up."
    Tasks: 2
   Memory: 676.0K
   CGroup: /system.slice/avahi-daemon.service
           ├─36457 avahi-daemon: running [hpc-r001.local]
           └─36494 avahi-daemon: chroot helper
.....
.....
.....
 

Unable to Stop ???

I tried to stop it, but the daemon did not stop….. Hmmmmm

# systemctl stop avahi-daemon
Warning: Stopping avahi-daemon.service, but it can still be activated by:
  avahi-daemon.socket
[root@hpc-r001 ~]# systemctl status avahi-daemon
● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
   Loaded: loaded (/usr/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2023-08-28 23:11:54 +08; 10s ago
 Main PID: 372559 (avahi-daemon)
   Status: "avahi-daemon 0.6.31 starting up."
    Tasks: 2
   Memory: 704.0K
   CGroup: /system.slice/avahi-daemon.service
           ├─372559 avahi-daemon: running [hpc-r001.local]
           └─372563 avahi-daemon: chroot helper

Unable to Disable ???

I tried to disable as well. But…… still alive?

# systemctl disable avahi-daemon
Removed symlink /etc/systemd/system/multi-user.target.wants/avahi-daemon.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.Avahi.service.
Removed symlink /etc/systemd/system/sockets.target.wants/avahi-daemon.socket.
[root@hpc-r001 ~]# systemctl status avahi-daemon
● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
   Loaded: loaded (/usr/lib/systemd/system/avahi-daemon.service; disabled; vendor preset: enabled)
   Active: active (running) since Mon 2023-08-28 23:12:25 +08; 2min 32s ago
 Main PID: 372707 (avahi-daemon)
   Status: "avahi-daemon 0.6.31 starting up."
   CGroup: /system.slice/avahi-daemon.service
           ├─372707 avahi-daemon: running [hpc-r001.local]
           └─372709 avahi-daemon: chroot helper

Finally…… Mask, Disable then stop.

To prevent a service from running you need to “mask” it first

# systemctl mask avahi-daemon
Created symlink from /etc/systemd/system/avahi-daemon.service to /dev/null.
# systemctl disable avahi-daemon
# systemctl stop avahi-daemon

# systemctl status avahi-daemon
● avahi-daemon.service
   Loaded: masked (/dev/null; bad)
   Active: inactive (dead) since Mon 2023-08-28 23:15:42 +08; 20min ago
 Main PID: 372707 (code=exited, status=0/SUCCESS)