Check VNC port

You can check VNC port of each instance 


Where <instance-0000001b> is that one you want to check.
#lsof -i | grep $(ps aux | grep instance-0000001b | grep -v grep | awk '{ print$2 }')
kvm       22284 libvirt-qemu   14u  IPv4  86219      0t0  TCP *:5902 (LISTEN)