If your domain name is set correctly, ypbind is running, and you get messages indicating that the client cannot communicate with a server, this might indicate a number of different problems:
Does the client have a /var/yp/binding/domainname/ypservers file containing a list of servers to bind to? If not, run ypinit -c and specify in order of preference the servers that this client should bind to.
If the client does have a /var/yp/binding/domainname/ypservers file, are there enough servers listed in it if one or two become unavailable? If not, add additional servers to the list by running ypinit -c.
Do the servers listed in a clients ypservers file have entries in the /etc/hosts file? If not, add the servers to the NIS maps hosts input file and rebuild your maps by running yppinit -c or ypinit -s as described Working With NIS Maps.
Is the /etc/nsswitch.conf file set up to consult the machine's local hosts file in addition to NIS? See Chapter 2, The Name Service Switch (Overview) for more information on the switch.
Is the /etc/nsswitch.conf file set up to consult files first for services and rpc? See Chapter 2, The Name Service Switch (Overview) for more information on the switch.