redhat配置dns服务器bind
配置Oracle11g的RAC需要使用DNS服务器来解析SCAN IP，本文就是以此为例介绍bind服务器的使用。首先科普一下bind服务器,属于企业级产品了，还是开源的：
Bind是Berkeley Internet Name Domain Service的简写，它是一款实现DNS服务器的开放源码软件。Bind原本是美国DARPA资助伯克利大学（Berkeley）开设的一个研究生课题，后来经过多年的变化发展，已经成为世界上使用最为广泛的DNS服务器软件，目前Internet上半数以上的DNS服务器有都是用Bind来架设的。参考文档:http://www.cnblogs.com/luoahong/p/7859000.html
内网使用的简单场合就使用基本的功能足够了。要使用内网的dns服务器解析，每个主机都有配置本地的服务器。linux中的配置就在/etc/resolv.conf文件修改。配置方法参考下面：
/etc/resolv.conf 该文件是DNS域名解析的配置文件，它的格式很简单，每行以一个关键字开头，后接配置参数。 resolv.conf的关键字主要有四个，分别是： nameserver #定义DNS服务器的IP地址 domain #定义本地域名 search #定义域名的搜索列表 sortlist #对返回的域名进行排序 详细说明： nameserver 表明DNS服务器的IP地址。可以有很多行的nameserver，每一个带一个IP地址。在查询时就按nameserver在本文件中的顺序进行， 且只有当第一个nameserver没有反应时才查询下面的nameserver。 domain 声明主机的域名。很多程序用到它，如邮件系统；当为没有域名的主机进行DNS查询时，也要用到。 如果没有域名，主机名将被使用，删除所有在第一个点( .)前面的内容。 search 它的多个参数指明域名查询顺序。当要查询没有域名的主机，主机将在由search声明的域中分别查找。 domain和search不能共存；如果同时存在，后面出现的将会被使用。 sortlist 允许将得到域名结果进行特定的排序。它的参数为网络/掩码对，允许任意的排列顺序。 /etc/resolv.conf的一个示例： domain centoscn.com search www.centocn.com www.wgjlb.com nameserver 202.96.128.86 nameserver 202.96.128.166 最主要是nameserver关键字，如果没指定nameserver就找不到DNS服务器，其它关键字是可选的。Red Hat中没有提供缺省的/etc/resolv.conf文件，它的内容是根据在安装时给出的选项动态创建的。
redhat主机地址：192.168.2.60 。本地域名:localdomain，因为安装了bind-chroot，修改配置文件就在/var/named/chroot/etc/named.conf,/etc/named.conf则无效(bind运行后chroot的etc里面的name.rfc1912.zones好像会更新到/etc里面的name.rfc1912.zones)。
（In the zone definitions we defined the file containing the zone configuration. These files are located in the "/var/named/" directory. If you are using the "chroot" version of BIND, the location of the following files will be "/var/named/chroot/var/named" and you may need to change their group ownership to "named".）
此文件可以从该目录下named.caching-nameserver.conf复制而来。
配置信息如下：
options { listen-on port 53 { any; }; //所有机器都可以使用该dns服务器查询 listen-on-v6 port 53 { ::1; }; //ip v6格式的写法，同上一个意思 directory "/var/named"; dump-file "/var/named/data/cache_dump.db"; statistics-file "/var/named/data/named_stats.txt"; memstatistics-file "/var/named/data/named_mem_stats.txt"; // query-source port 53; // query-source-v6 port 53; allow-query { any; }; allow-query-cache { any; }; }; logging { channel default_debug { file "data/named.run"; severity dynamic; }; }; view localhost_resolver { match-clients { any; }; match-destinations { any; }; recursion yes; include "/etc/named.rfc1912.zones"; };
然后配置正向ZONE和反向ZONE，配置文件为/var/named/chroot/etc/named.rfc1912.zones。因为现在我们的本地域名设置为localdomain，默认情况下zone文件里面在第15到第20行已经包含了localdomain域名的正向解析配置了，所以不用添加。如果本地域名适用其他域名如xxx.com之类，就需要参照localdomain的配置来修改即可。
15 zone "localdomain" IN { 16 type master; 17 file "localdomain.zone"; 18 allow-update { none; }; 19 };
或者：
zone "xxx.com" IN {
type master;
file "xxx.com.zone";
allow-update { none; };
};
反向配置则根据内网网段来配置，本地网段：192.168.2.0/24，另外一个网段为：10.10.10.0/24所以配置为：
zone "2.168.192.in-addr.arpa" IN { type master; file "2.168.192.in-addr.arpa"; allow-update { none; }; }; zone "10.10.10.in-addr.arpa" IN { type master; file "10.10.10.in-addr.arpa"; allow-update { none; }; };
接着，配置正反向解析数据库文件。利用/var/named/chroot/var/named/localhost.zone 复制生成正向解析的数据库文件，利用/var/named/chroot/var/named/localhost.zone 复制生成名为2.168.192.in-addr.arpa 的反向解析的数据库文件，记得带-p参数传递权限。
[root@linux named]# cp -p localhost.zone ./localdomain.zone [root@linux named]# cp -p localhost.zone ./2.168.192.in-addr.arpa
再编辑解析数据库文件，使用不带域名后缀的short name即可。具体RAC环境的网络规划为：
| Host name |
Short hostname |
IP type |
IP address |
Interface |
| snode1.localdomain |
snode1 |
Public ip |
192.168.2.21 |
eth0 |
| snode1-vip.localdomain |
snode1-vip |
Virtual ip |
192.168.2.22 |
eth0:1 |
| snode1-priv.localdomain |
snode1-priv |
Private ip |
10.10.10.21 |
eth1 |
| snode2.localdomain |
snode2 |
Public ip |
192.168.2.24 |
eth0 |
| snode2-vip.localdomain |
snode2-vip |
Virtual ip |
192.168.2.25 |
eth0:1 |
| snode2-priv.localdomain |
snode2-priv |
Private ip |
10.10.10.22 |
eth1 |
| pnode1.localdomain |
pnode1 |
Public ip |
192.168.2.11 |
eth0 |
| pnode1-vip.localdomain |
pnode1-vip |
Virtual ip |
192.168.2.12 |
eth0:1 |
| pnode1-priv.localdomain |
pnode1-priv |
Private ip |
10.10.10.11 |
eth1 |
| pnode2.localdomain |
pnode2 |
Public ip |
192.168.2.14 |
eth0 |
| pnode2-vip.localdomain |
pnode2-vip |
Virtual ip |
192.168.2.15 |
eth0:1 |
| pnode2-priv.localdomain |
pnode2-priv |
Private ip |
10.10.10.12 |
eth1 |
| scan-cluster.localdomain |
scan-cluster |
Scan ip |
192.168.2.23 |
eth0 |
| scan-cluster.localdomain |
scan-cluster |
Scan ip |
192.168.2.26 |
eth0 |
| scan-cluster.localdomain |
scan-cluster |
Scan ip |
192.168.2.13 |
eth0 |
配置完成的解析数据库文件为：
[root@linux named]# vim localdomain.zone $TTL 86400 @ IN SOA localhost root ( 42 ; serial (d. adams) 3H ; refresh 15M ; retry 1W ; expiry 1D ) ; minimum IN NS localhost localhost IN A 127.0.0.1 pnode1 IN A 192.168.2.11 pnode1-vip IN A 192.168.2.12 pnode1-priv IN A 10.10.10.11 pnode2 IN A 192.168.2.14 pnode2-vip IN A 192.168.2.15 pnode2-priv IN A 10.10.10.12 snode1 IN A 192.168.2.21 snode1-vip IN A 192.168.2.22 snode1-priv IN A 10.10.10.21 snode2 IN A 192.168.2.24 snode2-vip IN A 192.168.2.25 snode2-priv IN A 10.10.10.22 scan-cluster IN A 192.168.2.13 scan-cluster IN A 192.168.2.23 scan-cluster IN A 192.168.2.26
[root@linux named]# vim 2.168.192.in-addr.arpa $TTL 86400 @ IN SOA localhost. root.localhost. ( 1997022700 ; Serial 28800 ; Refresh 14400 ; Retry 3600000 ; Expire 86400 ) ; Minimum IN NS localhost. 60 IN PTR localhost. 11 IN PTR pnode1.localdomain 12 IN PTR pnode1-vip.localdomain 14 IN PTR pnode2.localdomain 15 IN PTR pnode2-vip.localdomain 21 IN PTR snode1.localdomain 22 IN PTR snode1-vip.localdomain 24 IN PTR snode2.localdomain 25 IN PTR snode2-vip.localdomain 23 IN PTR scan-cluster.localdomain 26 IN PTR scan-cluster.localdomain 13 IN PTR scan-cluster.localdomain
重启bind：/etc/init.d/named restart
验证解析结果，正向:
[root@linux named]# nslookup snode1 up scan-cluster nslookup scan-clusterServer: 192.168.2.60 Address: 192.168.2.60#53 Name: snode1.localdomain Address: 192.168.2.21 [root@linux named]# nslookup snode1-vip Server: 192.168.2.60 Address: 192.168.2.60#53 Name: snode1-vip.localdomain Address: 192.168.2.22 [root@linux named]# nslookup snode1-priv Server: 192.168.2.60 Address: 192.168.2.60#53 Name: snode1-priv.localdomain Address: 10.10.10.21 [root@linux named]# nslookup snode2 Server: 192.168.2.60 Address: 192.168.2.60#53 Name: snode2.localdomain Address: 192.168.2.24 [root@linux named]# nslookup snode2-vip Server: 192.168.2.60 Address: 192.168.2.60#53 Name: snode2-vip.localdomain Address: 192.168.2.25 [root@linux named]# nslookup snode2-priv Server: 192.168.2.60 Address: 192.168.2.60#53 Name: snode2-priv.localdomain Address: 10.10.10.22 [root@linux named]# nslookup pnode1 Server: 192.168.2.60 Address: 192.168.2.60#53 Name: pnode1.localdomain Address: 192.168.2.11 [root@linux named]# nslookup pnode1-vip Server: 192.168.2.60 Address: 192.168.2.60#53 Name: pnode1-vip.localdomain Address: 192.168.2.12 [root@linux named]# nslookup pnode1-priv Server: 192.168.2.60 Address: 192.168.2.60#53 Name: pnode1-priv.localdomain Address: 10.10.10.11 [root@linux named]# nslookup pnode2 Server: 192.168.2.60 Address: 192.168.2.60#53 Name: pnode2.localdomain Address: 192.168.2.14 [root@linux named]# nslookup pnode2-vip Server: 192.168.2.60 Address: 192.168.2.60#53 Name: pnode2-vip.localdomain Address: 192.168.2.15 [root@linux named]# nslookup pnode2-priv Server: 192.168.2.60 Address: 192.168.2.60#53 Name: pnode2-priv.localdomain Address: 10.10.10.12 [root@linux named]# nslookup scan-cluster Server: 192.168.2.60 Address: 192.168.2.60#53 Name: scan-cluster.localdomain Address: 192.168.2.13 Name: scan-cluster.localdomain Address: 192.168.2.23 Name: scan-cluster.localdomain Address: 192.168.2.26
反向：
[root@linux etc]# nslookup 192.168.2.21 Server: 192.168.2.60 Address: 192.168.2.60#53 21.2.168.192.in-addr.arpa name = snode1.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.22 Server: 192.168.2.60 Address: 192.168.2.60#53 22.2.168.192.in-addr.arpa name = snode1-vip.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 10.10.10.21 Server: 192.168.2.60 Address: 192.168.2.60#53 21.10.10.10.in-addr.arpa name = snode1-priv.localdomain.10.10.10.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.24 Server: 192.168.2.60 Address: 192.168.2.60#53 24.2.168.192.in-addr.arpa name = snode2.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.25 Server: 192.168.2.60 Address: 192.168.2.60#53 25.2.168.192.in-addr.arpa name = snode2-vip.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 10.10.10.22 Server: 192.168.2.60 Address: 192.168.2.60#53 22.10.10.10.in-addr.arpa name = snode2-priv.localdomain.10.10.10.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.11 Server: 192.168.2.60 Address: 192.168.2.60#53 11.2.168.192.in-addr.arpa name = pnode1.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.12 Server: 192.168.2.60 Address: 192.168.2.60#53 12.2.168.192.in-addr.arpa name = pnode1-vip.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 10.10.10.11 Server: 192.168.2.60 Address: 192.168.2.60#53 11.10.10.10.in-addr.arpa name = pnode1-priv.localdomain.10.10.10.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.14 Server: 192.168.2.60 Address: 192.168.2.60#53 14.2.168.192.in-addr.arpa name = pnode2.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.15 Server: 192.168.2.60 Address: 192.168.2.60#53 15.2.168.192.in-addr.arpa name = pnode2-vip.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 10.10.10.12 Server: 192.168.2.60 Address: 192.168.2.60#53 12.10.10.10.in-addr.arpa name = pnode2-priv.localdomain.10.10.10.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.23 Server: 192.168.2.60 Address: 192.168.2.60#53 23.2.168.192.in-addr.arpa name = scan-cluster.localdomain.2.168.192.in-addr.arpa. [root@linux etc]# nslookup 192.168.2.26 Server: 192.168.2.60 Address: 192.168.2.60#53 26.2.168.192.in-addr.arpa name = scan-cluster.localdomain.2.168.192.in-addr.arpa.
说明配置成功。剩下的工作就是配置网络内其他主机的默认dns服务器地址就可以使用了。
但是在配置其他主机的DNS的服务器时我们通常使用/etc/resolv.conf文件来修改，但是我测试在centos7中修改后/etc/init.d/network restart重启网络，发现/etc/resolv.conf文件又被复原了，但是不重启网络又不能使DNS设置生效。如果是这样，解决方法就是修改网络接口的DNS配置，即/etc/sysconfig/network-script/ifcfg-ethN中增加dns的选项。参考https://blog.csdn.net/kadwf123/article/details/78786947。
具体步骤关闭NetworkManager是关键，方法如下：
[root@localhost etc]# service NetworkManager stop
Redirecting to /bin/systemctl stop NetworkManager.service[root@localhost etc]# /bin/systemctl stop NetworkManager.service
[root@localhost etc]# service NetworkManager status
Redirecting to /bin/systemctl status NetworkManager.service
● NetworkManager.service - Network Manager
Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; disabled; vendor preset: enabled)
Active: inactive (dead) since Wed 2019-05-08 23:29:19 CST; 29s ago
Process: 10904 ExecStart=/usr/sbin/NetworkManager --no-daemon (code=exited, status=0/SUCCESS)
Main PID: 10904 (code=exited, status=0/SUCCESS)
CGroup: /system.slice/NetworkManager.service
└─12251 /sbin/dhclient -d -q -sf /usr/libexec/nm-dhcp-helper -pf /...[root@localhost etc]# chkconfig NetworkManager off
Note: Forwarding request to 'systemctl disable NetworkManager.service'.
[root@localhost etc]# systemctl disable NetworkManager.service
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