How do I solve the "refused connect from <ip> to procedure <X>" message I get when running a NIS server on Red Hat Enterprise Linux?

Issue

• Why are new users created in my NIS server not visible on my NIS client in Red Hat Enterprise Linux system even after rebuilding the maps?
• Why is logging in using NIS so slow?
• Why do I see the following errors in my logs for the procedure ypproc_match?

Mar 19 14:57:06 hostname ypserv[3778]: refused connect from 10.0.0.1:8762 to procedure ypproc_match (nisdomain,passwd.adjunct.byname;-1)

• Why do I see the following errors in my logs for the procedure ypproc_clear?

Mar 19 14:57:06 hostname ypserv[3778]: refused connect from 127.0.0.1:725 to procedure ypproc_clear (,;0)