Strange status on CARP

[Perun]

I have a strange status in CARP interfaces:

Code Select Expand

DMZ 40 (freq. 3/3) 192.168.40.2   MASTER
DMZ 46 (freq. 3/0) 2a02:8106:39:e601::2   MASTER
LAN 50 (freq. 3/3) 192.168.50.2   MASTER
LAN 56 (freq. 3/0) 2a02:8106:39:e605::2   MASTER
MEDIA 150 (freq. 3/3) 192.168.150.2   MASTER
MEDIA 156 (freq. 3/3) 2a02:8106:39:e615::2   MASTER
IOT 124 (freq. 3/3) 192.168.24.2   MASTER
IOT 126 (freq. 3/3) 2a02:8106:39:e624::2   MASTER
VMWARE 248 (freq. 3/3) 192.168.48.2   MASTER
VMWARE 246 (freq. 3/3) 2a02:8106:39:e648::2   MASTER
why are some in freq. 3/0? What does it mean?

on the backup CARP i see this:

Code Select Expand

DMZ 40 (freq. 4/103) 192.168.40.2   BACKUP
DMZ 46 (freq. 4/0) 2a02:8106:39:e601::2   BACKUP
LAN 50 (freq. 4/103) 192.168.50.2   BACKUP
LAN 56 (freq. 4/100) 2a02:8106:39:e605::2   BACKUP
IOT 124 (freq. 4/103) 192.168.24.2   BACKUP
IOT 126 (freq. 4/103) 2a02:8106:39:e624::2   BACKUP
MEDIA 150 (freq. 4/103) 192.168.150.2   BACKUP
MEDIA 156 (freq. 4/103) 2a02:8106:39:e615::2   BACKUP
VMWARE 246 (freq. 4/103) 2a02:8106:39:e648::2   BACKUP
VMWARE 248 (freq. 4/103) 192.168.48.2   BACKUP
Greetz