An entry like "ypserver myhost.my.domain" in /etc/yp.conf, where the used hostname is listed in /etc/hosts (and actually is the name of local host, because I tested it on a slave server) does not work, while replacing the hostname with its IP address works fine. The comment lines in /etc/yp.conf suggest something else and on a very old system (RHL 3.0.3) this also worked fine.
Check /etc/nsswitch.conf and make sure you have something like hosts: files dns nisplus nis
Checked, /etc/nsswitch.conf is unchanged, so it says: hosts: files nisplus nis dns
hmm, can't seem to duplicate this here. Sounds like a DNS issue though, not a ypbind issue -- I am using hostnames not IP addresses in /etc/yp.conf just fine.