NIS服务器生成数据库的时候出错：Unknown hostUpdating protocols...
目标：将主机A配置为nis服务器，nis域名为testnis，主机A的nis域名为yangbo.testnis
步骤如下：

1. 修改/etc/sysconfig/network文件， 加入一行：NISDOMAIN=testnis,即配置nis域名为testnis，并且修改HOSTNAME为yangbo.testnis
2. hostname命令修改主机名为yangbo.testnis
3. 修改/etc/hosts文件，将127.0.0.1这一行改为：127.0.0.1               yangbo.testnis yangbo yangbo
4. 启动ypserv，yppasswdd服务成功
5. rpcinfo查询ypserv和yppasswd已经成功使用了RPC服务:
         运行 rpcinfo -u yangbo ypserv，结果为
                program 100004 version 1 ready and waiting
                program 100004 version 2 ready and waiting
         运行 rpcinfo -u yangbo yppasswdd，结果为
                program 100009 version 1 ready and waiting
6. 建立NIS数据库，这一步遇到了问题，系统提示：failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating passwd.byuid...

--------我到网上查，有些人是说这是因为找不到的主机及ip 对应关系，可是在/etc/hosts文件中，这个映射关系我已经建立了阿。莫非我配置的不对？请问该怎么配置？
[root@yangbo ~]# /usr/lib/yp/ypinit -m

At this point, we have to construct a list of the hosts which will run NIS
servers. yangbo.testnis is in the list of NIS server hosts.  Please continue toadd                                                                              
the names for the other hosts, one per line.  When you are done with the         
list, type a .                                                        
        next host to add:  yangbo.testnis                                        
        next host to add:                                                        
The current list of NIS servers looks like this:                                 

yangbo.testnis

Is this correct?  [y/n: y]  y
We need a few minutes to build the databases...
Building /var/yp/testnis/ypservers...         
Running /var/yp/Makefile...                   
gmake[1]: Entering directory `/var/yp/testnis'
Updating passwd.byname...                     
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating passwd.byuid...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating group.byname...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating group.bygid...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating hosts.byname...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating hosts.byaddr...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating rpc.byname...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating rpc.bynumber...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating services.byname...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating services.byservicename...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating netid.byname...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating protocols.bynumber...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating protocols.byname...
failed to send 'clear' to local ypserv: RPC: Unknown hostUpdating mail.aliases...
failed to send 'clear' to local ypserv: RPC: Unknown hostgmake[1]: Leaving directory `/var/yp/testnis'

yangbo.testnis has been set up as a NIS master server.

Now you can run ypinit -s yangbo.testnis on all slave server.