Some systems were found to be responding to mDNS requests (5353/udp). Linux hosts were running the avahi-daemon which provides this service. As the auto-discovery service is not used for service identification, the avahi-daemon was disabled.

Confirm response is seen on 5353/udp prior to change:

nmap -P0 -p 5353 -sU hostname.example.net

SSH to host identified as responding to mDNS requests. Disable the avahi-daemon then stop the avahi-daemon:

systemctl disable avahi-daemon
systemctl stop avahi-daemon

 

Verify that 5353/udp is no longer open by repeating the nmap command.

Fin.