Often on FreeBSD servers you can see the pfsync0 pseudo-interface up:

[root@bsd ~]# ifconfig
pfsync0: flags=0<> mtu 2020 
 syncpeer: maxupd: 128

Unless you are running a pf firewall with redundancy, you won't need this, moreover on CPanel/WHM enabled servers, Cpanel sometimes tries to assign this multicast ip to a domain/customer.

You can safely disable it by adding:


to /etc/rc.conf