GMS and administration use different protocols for cluster operations.
GMS in 3.1.2 is based on UDP multicast. Cluster administration is based
on HTTP and SSH (both TCP protocols) using the nodehost values in the
nodes. So it is indeed possible that these two subsystems can get a
different view of the world.
Have you established that basic networking from the DAS to node YYY is
working. Try starting the second instancde (i26) and then (from the DAS
host), run "telnet YYY.com 24848". You should be able to connect. Also,
try "nslookup YYY.com" and make sure the IP address is different than
that for "nslookup XXX.com" (when run from the DAS). Is "asadmin
start-instance i26" (run from the DAS) working? Or are you running
start-local-instance from YYY.com?
Tom