For the longest time, I found my console littered with messages like the one below:

arp: 192.168.0.116 moved from b0:df:3a:04:af:9a to 6c:ad:f8:30:a7:c0 on bge0

If you have NIC teaming in your environment (or if you re-assign a IP address to another machine or a new interface) you’re likely to have this message show up many, many times. There are certainly specific circumstances where this information would be helpful, but on my home network - none of those exist.

Here’s how you quiet that bit of noise - found via arp(4)

sysctl net.link.ether.inet.log_arp_movements=0

If you want to have the change survive a reboot you’ll need to add this line to your /etc/sysctl.conf file:

net.link.ether.inet.log_arp_movements=0

That’s it! Once that sysctl setting in place, the kernel will no longer log (and notify) you when a IP address moves from one MAC address to another.