问题描述：DNS配置好后进行测试报错"server can't find xxxxxx: NXDOMAIN",如下所示：
系统：OEL 5.5 64位
DNS服务器IP：192.168.0.145
1、问题重现
[root@dns named]# service named restart
Stopping named:                                            [  OK  ]
Starting named:                                            [  OK  ]
[root@dns named]# netstat -tnlp | grep 53
tcp        0      0 192.168.0.145:53            0.0.0.0:*                   LISTEN      15694/named         
tcp        0      0 127.0.0.1:53                0.0.0.0:*                   LISTEN      15694/named         
tcp        0      0 127.0.0.1:953               0.0.0.0:*                   LISTEN      15694/named         
tcp        0      0 ::1:53                      :::*                        LISTEN      15694/named         
tcp        0      0 ::1:953                     :::*                        LISTEN      15694/named     

[root@dns ~]# nslookup scan.leo.com
Server:         192.168.0.1
Address:        192.168.0.1#53

** server can't find scan.leo.com: NXDOMAIN

[root@dns ~]# nslookup 192.168.0.195
Server:         192.168.0.1
Address:        192.168.0.1#53

195.0.168.192.in-addr.arpa      name = 192.168.0.195.

说明：如上所示，端口53正常，但是在DNS服务器上进行正向&方向解析均出现异常，但有趣的是rac1&rac2节点却能正常解析,如下所示：
[root@rac1 network-scripts]# nslookup scan.leo.com
Server:         192.168.0.145
Address:        192.168.0.145#53

Name:   scan.leo.com
Address: 192.168.0.195
Name:   scan.leo.com
Address: 192.168.0.196
Name:   scan.leo.com
Address: 192.168.0.197

[root@rac2 network-scripts]# nslookup 192.168.0.195
Server:         192.168.0.145
Address:        192.168.0.145#53

195.0.168.192.in-addr.arpa      name = scan.leo.com.

2、排错过程
根据异常信息，可以判断问题一定出在DNS服务器配置上.
A、为什么DNS服务器显示的Server为192.168.0.1，而rac1显示的为192.168.0.145？

网上资料显示文件属主错误会导致该异常，如下所示可排除该推断.
[root@dns named]# ll
total 44
-rw-r----- 1 root  named  507 Dec  2 14:03 0.168.192.local
drwxrwx--- 2 named named 4096 Dec  2 14:20 data
-rw-r----- 1 root  named  543 Dec  2 13:59 leo.com.zone
-rw-r----- 1 root  named  198 Jan 21  2010 localdomain.zone
-rw-r----- 1 root  named  195 Jan 21  2010 localhost.zone
-rw-r----- 1 root  named  427 Jan 21  2010 named.broadcast
-rw-r----- 1 root  named 1892 Jan 21  2010 named.ca
-rw-r----- 1 root  named  424 Jan 21  2010 named.ip6.local
-rw-r----- 1 root  named  426 Jan 21  2010 named.local
-rw-r----- 1 root  named  427 Jan 21  2010 named.zero
drwxrwx--- 2 named named 4096 Jul 27  2004 slaves
[root@dns etc]# ll
total 24
-rw-r--r-- 1 root root   389 Dec  2 12:27 localtime
-rw-r----- 1 root named 1230 Jan 21  2010 named.caching-nameserver.conf
-rw-r----- 1 root named 1192 Dec  2 14:20 named.conf
-rw-r----- 1 root named  955 Jan 21  2010 named.rfc1912.zones
-rw-r----- 1 root named  513 Dec  2 13:47 named.zones
-rw-r----- 1 root named  113 Dec  2 13:28 rndc.key

查看节点2 resolv.conf文件，显示nameserver为192.168.0.145
[root@rac2 network-scripts]# cat /etc/resolv.conf
; generated by /sbin/dhclient-script
search leo.com 
nameserver 192.168.0.145

此时查看dns服务器该参数，如下：
[root@dns ~]# cat /etc/resolv.conf
nameserver 192.168.0.1

3、解决方案
从以上可知，将DNS服务器/etc/resolv.conf文件按如下修改.
[root@dns ~]# vi /etc/resolv.conf
nameserver 192.168.0.145
search leo.com

[root@dns ~]# nslookup scan.leo.com
Server:         192.168.0.145
Address:        192.168.0.145#53

Name:   scan.leo.com
Address: 192.168.0.197
Name:   scan.leo.com
Address: 192.168.0.195
Name:   scan.leo.com
Address: 192.168.0.196

[root@dns ~]# nslookup 192.168.0.197
Server:         192.168.0.145
Address:        192.168.0.145#53

197.0.168.192.in-addr.arpa      name = scan.leo.com.

说明：如上所示，修改后成功解析.

参考文档：
https://blog.csdn.net/m0_65482363/article/details/130395682
https://blog.csdn.net/weixin_39888807/article/details/116883764