RHEL 7 上安装DNS服务器可以实现域名与IP的双向解析，即通过域名可以找到主机IP，也可以通过IP找到域名。在postfix搭建邮件服务器中，需要用到DNS正向解析与反向解析，因此DNS服务器大有可为。
首先需要安装bind，它是named服务的依赖，我们搭建DNS服务器就是要使用named服务，无需像有些文章所说的安装bind-chroot，另外我们需要通过一些命令比如nslookup,dig来检验我们的DNS服务是否正常，我们需要安装bind-utils，整个DNS服务器的安装，就只需要安装bind、bind-utils，剩下的就是配置正向解析与反向解析。
1.安装bind、bind-utils
[root@OpsNote ~]# yum install -y bind bind-utils已加载插件：langpacks, product-id, subscription-managerThis system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.aa | 4.1 kB 00:00:00 软件包 32:bind-utils-9.9.4-14.el7.x86_64 已安装并且是最新版本正在解决依赖关系--> 正在检查事务---> 软件包 bind.x86_64.32.9.9.4-14.el7 将被 安装--> 解决依赖关系完成依赖关系解决=============================================================================================================================================================================================== Package 架构 版本 源 大小===============================================================================================================================================================================================正在安装: bind x86_64 32:9.9.4-14.el7 aa 1.8 M事务概要===============================================================================================================================================================================================安装 1 软件包总下载量：1.8 M安装大小：4.3 MDownloading packages:Running transaction checkRunning transaction testTransaction test succeededRunning transaction 正在安装 : 32:bind-9.9.4-14.el7.x86_64 1/1 验证中 : 32:bind-9.9.4-14.el7.x86_64 1/1 已安装: bind.x86_64 32:9.9.4-14.el7完毕！[root@OpsNote ~]# systemctl is-active namedinactive[root@OpsNote ~]#2.配置/etc/named.conf
vim /etc/named.conf #编辑配置文件 10 options { 11 listen-on port 53 { 127.0.0.1; }; #127.0.0.1更改为any 12 listen-on-v6 port 53 { ::1; }; 13 directory "/var/named"; 14 dump-file "/var/named/data/cache_dump.db"; 15 statistics-file "/var/named/data/named_stats.txt"; 16 memstatistics-file "/var/named/data/named_mem_stats.txt"; 17 allow-query { localhost; }; #localhost更改为any3.配置/etc/named.rfc1912.zones
增加一个正向解析与一个反向解析的配置，可以拷贝其他的zone 配置，如下所示opsnote.com和68.168.192.in-addr.arpa两个zone是新增的
4.创建正向和反向文件
拷贝/var/named/目录下named.localhost和named.loopback分别为我们在named.rfc1912.zones中设置的正向解析文件opsnote和反向解析文件opsnote.zone，注意文件名的对应
[root@OpsNote ~]# cd /var/named/[root@OpsNote named]# lsdata dynamic named.ca named.empty named.localhost named.loopback slaves[root@OpsNote named]# cp -p named.localhost opsnote[root@OpsNote named]# cp -p named.loopback opsnote.zone[root@OpsNote named]# lsdata dynamic named.ca named.empty named.localhost named.loopback opsnote opsnote.zone slaves[root@OpsNote named]#5.修改正向和反向文件
修改opsnote文件
[root@OpsNote named]# cat opsnote$TTL 1D@ IN SOA opsnote.com. rname.invalid. ( 0 ; serial 1D ; refresh 1H ; retry 1W ; expire 3H ) ; minimum NS @ A 127.0.0.1 AAAA ::1 NS ns.opsnote.com.ns IN A 192.168.10.135www IN A 192.168.10.201ftp IN A 192.168.10.202[root@OpsNote named]#修改opsnote.zone文件
[root@OpsNote named]# cat opsnote.zone $TTL 1D@ IN SOA opsnote.com. rname.invalid. ( 0 ; serial 1D ; refresh 1H ; retry 1W ; expire 3H ) ; minimum NS @ A 127.0.0.1 AAAA ::1 PTR localhost. NS ns.opsnote.com.ns A 192.168.68.135201 PTR www.opsnote.com.202 PTR ftp.opsnote.com.[root@OpsNote named]#注意：named配置文件在/etc目录下，而正向解析与反向解析文件均在/var/named文件夹下
6.更改正向和反向文件所有者
反向解析文件server.com.local的所属组不是named，那么将其修改为named
[root@OpsNote named]# ll 总用量 24drwxrwx---. 2 named named 6 1月 29 2014 datadrwxrwx---. 2 named named 6 1月 29 2014 dynamic-rw-r-----. 1 root named 2076 1月 28 2013 named.ca-rw-r-----. 1 root named 152 12月 15 2009 named.empty-rw-r-----. 1 root named 152 6月 21 2007 named.localhost-rw-r-----. 1 root named 168 12月 15 2009 named.loopback-rw-r-----. 1 root named 285 9月 10 16:03 opsnote-rw-r-----. 1 root named 307 9月 10 16:05 opsnote.zonedrwxrwx---. 2 named named 6 1月 29 2014 slaves[root@OpsNote named]# chown named opsnote opsnote.zone [root@OpsNote named]# ll 总用量 24drwxrwx---. 2 named named 6 1月 29 2014 datadrwxrwx---. 2 named named 6 1月 29 2014 dynamic-rw-r-----. 1 root named 2076 1月 28 2013 named.ca-rw-r-----. 1 root named 152 12月 15 2009 named.empty-rw-r-----. 1 root named 152 6月 21 2007 named.localhost-rw-r-----. 1 root named 168 12月 15 2009 named.loopback-rw-r-----. 1 named named 285 9月 10 16:03 opsnote-rw-r-----. 1 named named 307 9月 10 16:05 opsnote.zonedrwxrwx---. 2 named named 6 1月 29 2014 slaves[root@OpsNote named]#7.启动服务
[root@OpsNote named]# cat /etc/resolv.conf # Generated by NetworkManagerdomain localdomainsearch localdomainnameserver 192.168.68.135[root@OpsNote named]# systemctl start named[root@OpsNote named]# firewall-cmd --add-service=dns success[root@OpsNote named]#8.测试
在另外一台rhel 7（192.168.68.131）上面配置好DNS:192.168.68.135，测试
[root@localhost ~]# ifconfig ens32ens32: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.68.131 netmask 255.255.255.0 broadcast 192.168.68.255 inet6 fe80::4c67:9a21:2e77:422a prefixlen 64 scopeid 0x20<link> ether 00:0c:29:56:1a:03 txqueuelen 1000 (Ethernet) RX packets 1674 bytes 1732919 (1.6 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 607 bytes 70284 (68.6 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0[root@localhost ~]# [root@localhost ~]# cat /etc/resolv.conf# Generated by NetworkManagersearch localdomainnameserver 192.168.68.135[root@localhost ~]# ping 192.168.68.135 -c1PING 192.168.68.135 (192.168.68.135) 56(84) bytes of data.64 bytes from 192.168.68.135: icmp_seq=1 ttl=64 time=1.60 ms--- 192.168.68.135 ping statistics ---1 packets transmitted, 1 received, 0% packet loss, time 0msrtt min/avg/max/mdev = 1.609/1.609/1.609/0.000 ms[root@localhost ~]# nslookup www.opsnote.comServer: 192.168.68.135Address: 192.168.68.135#53Name: www.opsnote.comAddress: 192.168.10.201[root@localhost ~]# nslookup ftp.opsnote.comServer: 192.168.68.135Address: 192.168.68.135#53Name: ftp.opsnote.comAddress: 192.168.10.202[root@localhost ~]# [root@localhost ~]# nslookup ns.opsnote.comServer: 192.168.68.135Address: 192.168.68.135#53Name: ns.opsnote.comAddress: 192.168.10.135[root@localhost ~]#