Not sure if this helps, but I was able to fix my issue with DNS. I checked syslog after a failed connection, and was seeing the following:
Which made me realize that spiceproxy is looking up hosts based on domain name, not IP. So I added my nodes to the hostfile, and that fixed my issues.
Code:
[COLOR=#000000][FONT=tahoma]Mar 10 08:21:35 C6100-1-N1 spiceproxy[100182]: WARNING: unable to get IP for node 'c6100-1-n4' - node offline?[/FONT][/COLOR]
[COLOR=#000000][FONT=tahoma]Mar 10 08:21:35 C6100-1-N1 spiceproxy[100182]: problem with client 10.1.6.1; unable to get IP for node 'c6100-1-n4' - node offline?[/FONT][/COLOR]