The Kerberos 5 KDC automatically listen on any interface (VLANs and VPNs included) on which you have configured one or more IP addresses. You just have to reboot the system or type the command
service kerberos5 restart
after that you have added or changed an IP.
To verify this, you just have to give the command
netstat -an | grep :88
that will show you the IP on which the KDC is bound.
You should never modify the IP address of the dummy1 interface (192.168.142.142) that is only used for internal communication with the KDC, because the kerberos daemon does not listen on the IP 127.0.0.1.