CentOS7部署DNS服务

爱被打了一巴掌 2022-01-22 00:29 457阅读 0赞

### DNS配置介绍 ###

#### 主配置文件/etc/named.conf ####

options {...};                设定DNS服务器全局环境
    
    listen-on port 53 {...;};     DNS服务named监听的端口和ip
    
    directory                     定义数据库文件存放的目录，即zone file的存放目录
    
    dump-file/statistics-file/memstatistics-file 
    
                                  关于named服务的统计信息的文件
    
    allow-query {...;};           允许询问我DNS服务器的主机
    
    allow-transfer {...;};        是否允许slave DNS对领域数据进行转发
    
    allow-update {...;};          动态DNS更新
    
    recursion                     是否支持递归查询，设置为no将不能访问根服务器
    
    forward                       是否支持转发
    
            only                  表示只进行转发
    
            first                 表示优先
    
            默认first
    
    forwarders {ip1;ip2;....;};   指定转发的上层DNS服务器IP
    
    zone "xxx" IN {...};          区域描述声明
    
            type                  指定zone类型
    
                hint              表示跟服务器
    
                master            表示该区域的主DNS服务器
    
                slave             表示该区域的从DNS服务器
    
            file                  表示DNS数据库文件放在哪里
    
    view " " {...};                域名视图描述声明
    
    acl "xxx" {...;};              定义访问控制列表，名字为xxx
    
            内置的acl：localhost/localnet/any/none:本地主机的IP/该局域网的所有IP/任何IP/所有都不
    
    include " ";                   将过多的zone声明写入一个文件当中，以免主配置文件过于繁琐

#### 数据库文件/var/named/\* ####

DNS服务器的数据库记录信息

$TTL       该区域的记录信息能够在客户端的缓存中存活多长时间
    
    SOA        一个区域的记录信息的开始，必须标识
    
        格式为：区域    IN    SOA    主DNS服务器域名    邮件服务器域名 (                    
    
                            serial;    序列号，从DNS的序列号如果小于它则会更新数据
    
                            refresh;   从DNS服务器多长时间检查一次主DNS的数据   
    
                            retry;     从DNS服务器连接主DNS失败后，多长时间后重新连接 
    
                            expire;    从DNS始终无法连接主DNS，从DNS的数据库文件何时失效
    
                            minimum;   如果DNS服务器查询结果失败，此失败信息会在缓存缓存中存活多长时间
    
                )
                
    NS        管理区域的DNS服务器名称，每个域名都有自己的NS记录，必须标识
    
    A         主机名对应的IPv4地址，必须标识
    
    AAAA      ipv6的地址
    
    MX        表示区域的邮件服务器的域名
    
    CNAME     主机别名，用于域名内部的跳转，为服务器配置提供灵活性。变更域名的IP地址的时候，只需要修改别名
    
        格式为：别名    IN    CNAME    DNS服务器的域名
    
    PTR       PoinTeR的缩写，逆向查询记录，后边记录的数据就是反解到的主机名，反向解析数据库文件必须标识

对于SOA部分，例如：

1804170045 
            5 
            5 
            2592000 
            3600
    
    表示：2018/4/17第45次刷新，slave每5秒连接master，连接失败则在5秒之后再次连接，直到2592000秒，查询失败的记录在其他DNS服务器中存活3600秒

#### DNS解析常用命令 ####

查询主机名IP的命令
    
            host [option] <FQDN> [server]
    
                    -a         列出详细信息
    
                    -l         列出domain所管理的所有主机名的信息
    
            nsloopup <FQDN> [server]
    
                    支持正解和反解
    
            dig [option] <FQDN> [@server]
    
                    +trace     从根服务器开始追踪
    
                    - t <type> 指定查询的数据类别
    
                    -x         反解查询
    
            whois <domain>
    
                    查询注册的domain的信息
    
                    该命令来自jwhois软件
    
    
    rndc reload     重新读取named.conf
    
    named-checkconf 检查主配置文件named.conf的语法

--------------------

### 安装DNS ###

*  规划：

1. 指定区域lzxlinux.com，该DNS服务器的域名为master.lzxlinux.com，同时有另外一个域名为www.lzxlinux.com；
    
    2. 该域名服务器有一个别名叫做ftp.lzxlinux.com；
    
    3. 该区域内有一台名为www.lzxlinux.com的邮件服务器；
    
    4. 该DNS服务器的IP为192.168.30.254，并且用同网段另一台机器192.168.30.131来测试；
    
    5. 该DNS服务器支持正向解析和反向解析。

> 一个服务器可以是一个IP对应多个域名，同样也可以一个域名对应多个IP。

*  安装：

yum install -y bind*

*  修改配置：

vim /etc/named.conf
    
    options { 
            listen-on port 53 {  192.168.30.254; };
            listen-on-v6 port 53 {  ::1; };
            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";
            recursing-file  "/var/named/data/named.recursing";
            secroots-file   "/var/named/data/named.secroots";
            allow-query     {  any; };
    
            recursion yes;
    
            dnssec-enable no;
            dnssec-validation no;
    
            /* Path to ISC DLV key */
            bindkeys-file "/etc/named.iscdlv.key";
    
            managed-keys-directory "/var/named/dynamic";
    
            pid-file "/run/named/named.pid";
            session-keyfile "/run/named/session.key";
    };
    
    logging { 
            channel default_debug { 
                    file "data/named.run";
                    severity dynamic;
            };
    };
    
    zone "." IN { 
            type hint;
            file "named.ca";
    };
    
    zone "lzxlinux.com" IN { 
        type master;
        file "named.lzxlinux.com";
    };
    
    zone "30.168.192.in-addr.arpa" IN {              #反解zone的格式，必须将IP倒着写
        type master;
        file "named.192.168.30";
    };
    
    include "/etc/named.rfc1912.zones";
    include "/etc/named.root.key";

*  修改正向解析数据库文件：

正解数据库文件中必须要有$TTL、SOA、NS、A记录

vim /var/named/named.lzxlinux.com
    
    $TTL 1D
    @                                       IN SOA  master.lzxlinux.com. www.lzxlinux.com. (
                                    2019053101      ; serial
                                            1D      ; refresh
                                            1H      ; retry
                                            1W      ; expire
                                            3H )    ; minimum
    @                           IN      NS      master.lzxlinux.com. ;
    @                           IN      MX      10 www.lzxlinux.com. ;
    master.lzxlinux.com.        IN      A       192.168.30.254 ;
    www.lzxlinux.com.           IN      A       192.168.30.254 ;
    ftp.lzxlinux.com.           IN      CNAME   www.lzxlinux.com. ;

*  修改反向解析数据库文件：

反解数据库文件中必须要有$TTL、SOA、NS、PTR记录

vim /var/named/named.192.168.30
    
    $TTL 1D
    @                                       IN SOA  master.lzxlinux.com. www.lzxlinux.com. (
                                    2019053101      ; serial
                                            1D      ; refresh
                                            1H      ; retry
                                            1W      ; expire
                                            3H )    ; minimum
    @                           IN      NS      master.lzxlinux.com. ;
    254                         IN      PTR     master.lzxlinux.com. ;
    254                         IN      PTR     www.lzxlinux.com. ;

*  启动named服务：

systemctl start named

*  解析测试：

到 192.168.30.131 上测试

vim /etc/sysconfig/network-scripts/ifcfg-ens33
    #DNS1="8.8.8.8" #禁掉外网DNS
    DNS1="192.168.30.254"
    
    yum install -y bind-utils

dig master.lzxlinux.com
    
    ; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> master.lzxlinux.com
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55468
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;master.lzxlinux.com.		IN	A
    
    ;; ANSWER SECTION:
    master.lzxlinux.com.	86400	IN	A	192.168.30.254
    
    ;; AUTHORITY SECTION:
    lzxlinux.com.		86400	IN	NS	master.lzxlinux.com.
    
    ;; Query time: 2 msec
    ;; SERVER: 192.168.30.254#53(192.168.30.254)
    ;; WHEN: Sun Jun 02 21:45:20 EDT 2019
    ;; MSG SIZE  rcvd: 78

正向解析成功。

dig -x 192.168.30.254
    
    ; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> -x 192.168.30.254
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7803
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 1, ADDITIONAL: 2
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;254.30.168.192.in-addr.arpa.	IN	PTR
    
    ;; ANSWER SECTION:
    254.30.168.192.in-addr.arpa. 86400 IN	PTR	www.lzxlinux.com.
    254.30.168.192.in-addr.arpa. 86400 IN	PTR	master.lzxlinux.com.
    
    ;; AUTHORITY SECTION:
    30.168.192.in-addr.arpa. 86400	IN	NS	master.lzxlinux.com.
    
    ;; ADDITIONAL SECTION:
    master.lzxlinux.com.	86400	IN	A	192.168.30.254
    
    ;; Query time: 1 msec
    ;; SERVER: 192.168.30.254#53(192.168.30.254)
    ;; WHEN: Sun Jun 02 21:50:03 EDT 2019
    ;; MSG SIZE  rcvd: 137

反向解析成功。

dig www.baidu.com
    
    ; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> www.baidu.com
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29209
    ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;www.baidu.com.			IN	A
    
    ;; ANSWER SECTION:
    www.baidu.com.		1083	IN	CNAME	www.a.shifen.com.
    www.a.shifen.com.	212	IN	A	115.239.211.112
    www.a.shifen.com.	212	IN	A	115.239.210.27
    
    ;; Query time: 7 msec
    ;; SERVER: 192.168.30.254#53(192.168.30.254)
    ;; WHEN: Sun Jun 02 21:50:47 EDT 2019
    ;; MSG SIZE  rcvd: 101

外网解析成功。

--------------------

### 配置主从DNS ###

每个域名中至少需要两台DNS服务器来管理该域名，提供不间断的查询服务，一个master，一个slave，slave自己没有数据库，需要从master那里同步，并且master需要开启数据库传输。

*  规划：

192.168.30.254作主DNS服务器，域名为master.lzxlinux.com，192.168.30.253作从DNS服务器，域名为slave.lzxlinux.com，他们共同管理区域lzxlinux.com

*  修改主DNS配置：

vim /etc/named.conf
    
    options { 
            listen-on port 53 {  192.168.30.254; };
            listen-on-v6 port 53 {  ::1; };
            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";
            recursing-file  "/var/named/data/named.recursing";
            secroots-file   "/var/named/data/named.secroots";
            allow-query     {  any; };
            allow-transfer {  none; };
            
            recursion yes;
    
            dnssec-enable no;
            dnssec-validation no;
    
            /* Path to ISC DLV key */
            bindkeys-file "/etc/named.iscdlv.key";
    
            managed-keys-directory "/var/named/dynamic";
    
            pid-file "/run/named/named.pid";
            session-keyfile "/run/named/session.key";
    };
    
    logging { 
            channel default_debug { 
                    file "data/named.run";
                    severity dynamic;
            };
    };
    
    zone "." IN { 
            type hint;
            file "named.ca";
    };
    
    zone "lzxlinux.com" IN { 
        type master;
        file "named.lzxlinux.com";
        allow-transfer {  192.168.30.253; };
    };
    
    zone "30.168.192.in-addr.arpa" IN { 
        type master;
        file "named.192.168.30";
        allow-transfer {  192.168.30.253; };
    };
    
    include "/etc/named.rfc1912.zones";
    include "/etc/named.root.key";

*  修改主DNS正向解析数据库文件：

vim /var/named/named.lzxlinux.com
    
    $TTL 1D
    @                                       IN SOA  master.lzxlinux.com. www.lzxlinux.com. (
                                    2019053101      ; serial
                                            1D      ; refresh
                                            1H      ; retry
                                            1W      ; expire
                                            3H )    ; minimum
    @                           IN      NS      master.lzxlinux.com. ;
    @                           IN      NS      slave.lzxlinux.com. ;
    @                           IN      MX      10 www.lzxlinux.com. ;
    master.lzxlinux.com.        IN      A       192.168.30.254 ;
    slave.lzxlinux.com.         IN      A       192.168.30.253 ;
    www.lzxlinux.com.           IN      A       192.168.30.254 ;
    ftp.lzxlinux.com.           IN      CNAME   www.lzxlinux.com. ;

*  修改主DNS反向解析数据库文件：

vim /var/named/named.192.168.30
    
    $TTL 1D
    @                                       IN SOA  master.lzxlinux.com. www.lzxlinux.com. (
                                    2019053101      ; serial
                                            1D      ; refresh
                                            1H      ; retry
                                            1W      ; expire
                                            3H )    ; minimum
    @                           IN      NS      master.lzxlinux.com. ;
    @                           IN      NS      slave.lzxlinux.com. ;
    254                         IN      PTR     master.lzxlinux.com. ;
    254                         IN      PTR     www.lzxlinux.com. ;
    253                         IN      PTR     slave.lzxlinux.com. ;

*  修改从DNS配置：

vim /etc/named.conf
    
    options { 
            listen-on port 53 {  localhost; };
            listen-on-v6 port 53 {  ::1; };
            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";
            recursing-file  "/var/named/data/named.recursing";
            secroots-file   "/var/named/data/named.secroots";
            allow-query     {  any; };
            allow-transfer {  none; };
            
            recursion yes;
    
            dnssec-enable no;
            dnssec-validation no;
    
            /* Path to ISC DLV key */
            bindkeys-file "/etc/named.iscdlv.key";
    
            managed-keys-directory "/var/named/dynamic";
    
            pid-file "/run/named/named.pid";
            session-keyfile "/run/named/session.key";
    };
    
    logging { 
            channel default_debug { 
                    file "data/named.run";
                    severity dynamic;
            };
    };
    
    zone "." IN { 
            type hint;
            file "named.ca";
    };
    
    zone "lzxlinux.com" IN { 
        type slave;
        file "slaves/named.lzxlinux.com";
        masters {  192.168.30.254; };
    };
    
    zone "30.168.192.in-addr.arpa" IN { 
        type slave;
        file "slaves/named.192.168.30";
        masters {  192.168.30.254; };
    };
    
    include "/etc/named.rfc1912.zones";
    include "/etc/named.root.key";

*  重启主从DNS上named服务：

systemctl restart named

从DNS上`/var/named/slaves/`目录中自动多出两个文件，这是从DNS同步主DNS的解析数据库

ll /var/named/slaves/
    
    total 8
    -rw-r--r-- 1 named named 383 Jun  3 10:51 named.192.168.30
    -rw-r--r-- 1 named named 449 Jun  3 10:51 named.lzxlinux.com

*  查看`/var/log/messages`日志，有同步传输过程：

vim /var/log/messages
    
    Jun  3 10:51:02 test6 named[6660]: zone 30.168.192.in-addr.arpa/IN: Transfer started.
    Jun  3 10:51:02 test6 named[6660]: transfer of '30.168.192.in-addr.arpa/IN' from 192.168.30.254#53: connected using 192.168.30.253#44120
    Jun  3 10:51:02 test6 named[6660]: zone 30.168.192.in-addr.arpa/IN: transferred serial 2019053101
    Jun  3 10:51:02 test6 named[6660]: transfer of '30.168.192.in-addr.arpa/IN' from 192.168.30.254#53: Transfer completed: 1 messages, 7 records, 220 bytes, 0.005 secs (44000 bytes/sec)
    Jun  3 10:51:02 test6 named[6660]: zone 30.168.192.in-addr.arpa/IN: sending notifies (serial 2019053101)
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.203.230.10#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:dc3::35#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.33.4.12#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.58.128.30#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:500:84::b#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.36.148.17#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 193.0.14.129#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:500:12::d0d#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 198.41.0.4#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:500:1::53#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 199.7.91.13#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.5.5.241#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 199.7.83.42#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:500:a8::e#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 202.12.27.33#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:500:2::c#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:503:c27::2:30#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.228.79.201#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:7fe::53#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:7fd::1#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 192.112.36.4#53
    Jun  3 10:51:02 test6 named[6660]: network unreachable resolving './NS/IN': 2001:503:ba3e::2:30#53
    Jun  3 10:51:02 test6 named[6660]: FORMERR resolving './NS/IN': 198.97.190.53#53
    Jun  3 10:51:02 test6 named[6660]: zone lzxlinux.com/IN: Transfer started.
    Jun  3 10:51:02 test6 named[6660]: transfer of 'lzxlinux.com/IN' from 192.168.30.254#53: connected using 192.168.30.253#56074
    Jun  3 10:51:02 test6 named[6660]: zone lzxlinux.com/IN: transferred serial 2019053101
    Jun  3 10:51:02 test6 named[6660]: transfer of 'lzxlinux.com/IN' from 192.168.30.254#53: Transfer completed: 1 messages, 9 records, 229 bytes, 0.033 secs (6939 bytes/sec)
    Jun  3 10:51:02 test6 named[6660]: zone lzxlinux.com/IN: sending notifies (serial 2019053101)

--------------------

### 配置子域DNS ###

*  规划：

192.168.30.254作主DNS服务器，域名为master.lzxlinux.com，192.168.30.253作从DNS服务器，域名为slave.lzxlinux.com，他们共同管理区域lzxlinux.com。
    
    在lzxlinux.com.下委派子域centos.lzxlinux.com.，192.168.30.128作子域的DNS服务器，域名是dns.centos.lzxlinux.com。

*  修改上层主DNS正向解析数据库文件：

vim /var/named/named.lzxlinux.com
    
    $TTL 1D
    @                                       IN SOA  master.lzxlinux.com. www.lzxlinux.com. (
                                    2019053101      ; serial
                                            1D      ; refresh
                                            1H      ; retry
                                            1W      ; expire
                                            3H )    ; minimum
    @                           IN      NS      master.lzxlinux.com. ;
    @                           IN      NS      slave.lzxlinux.com. ;
    @                           IN      MX      10 www.lzxlinux.com. ;
    centos.lzxlinux.com.        IN      NS      dns.centos.lzxlinux.com. ;
    dns.centos.lzxlinux.com.    IN      A       192.168.30.128 ;
    master.lzxlinux.com.        IN      A       192.168.30.254 ;
    slave.lzxlinux.com.         IN      A       192.168.30.253 ;
    www.lzxlinux.com.           IN      A       192.168.30.254 ;
    ftp.lzxlinux.com.           IN      CNAME   www.lzxlinux.com. ;

*  修改下层DNS配置：

> 注意：要开启子域DNS服务器的转发功能（forward），不开的话只能上层查询下层，下层查询不到上层

yum install -y bind*

vim /etc/named.conf
    
    options { 
            listen-on port 53 {  192.168.30.128; };
            listen-on-v6 port 53 {  ::1; };
            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";
            recursing-file  "/var/named/data/named.recursing";
            secroots-file   "/var/named/data/named.secroots";
            allow-query     {  any; };
            forward first;
            forwarders {  192.168.30.254; };
            
            recursion yes;
    
            dnssec-enable no;
            dnssec-validation no;
    
            /* Path to ISC DLV key */
            bindkeys-file "/etc/named.iscdlv.key";
    
            managed-keys-directory "/var/named/dynamic";
    
            pid-file "/run/named/named.pid";
            session-keyfile "/run/named/session.key";
    };
    
    logging { 
            channel default_debug { 
                    file "data/named.run";
                    severity dynamic;
            };
    };
    
    zone "." IN { 
            type hint;
            file "named.ca";
    };
    
    zone "centos.lzxlinux.com" IN { 
        type master;
        file "named.centos.lzxlinux.com";
    };
    
    include "/etc/named.rfc1912.zones";
    include "/etc/named.root.key";

*  修改下层DNS正向解析数据库文件：

> 注意：必须要指明邮件服务器 [www.centos.lzxlinux.com][].

vim /var/named/named.centos.lzxlinux.com
    
    $TTL 600
    @                                       IN SOA  dns.centos.lzxlinux.com. www.centos.lzxlinux.com. (
                                        2019053101  ; serial
                                            3600    ; refresh
                                            3600    ; retry
                                            3600    ; expire
                                            3600 )  ; minimum
    @                           IN      NS      dns.centos.lzxlinux.com. ;
    @                           IN      MX      10 www.centos.lzxlinux.com. ;
    dns                         IN      A       192.168.30.128 ;
    www                         IN      A       192.168.30.128 ;

*  重启上层主DNS和下层DNS上named服务：

systemctl restart named

*  解析测试：

1.  上层查询下层子域DNS服务器

dig dns.centos.lzxlinux.com @192.168.30.128
    
    ; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> dns.centos.lzxlinux.com @192.168.30.128
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57592
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;dns.centos.lzxlinux.com.	IN	A
    
    ;; ANSWER SECTION:
    dns.centos.lzxlinux.com. 600	IN	A	192.168.30.128
    
    ;; AUTHORITY SECTION:
    centos.lzxlinux.com.	600	IN	NS	dns.centos.lzxlinux.com.
    
    ;; Query time: 2 msec
    ;; SERVER: 192.168.30.128#53(192.168.30.128)
    ;; WHEN: Mon Jun 03 13:47:24 CST 2019
    ;; MSG SIZE  rcvd: 82

解析成功。

1.  下层查询上层DNS服务器：

dig master.lzxlinux.com @192.168.30.254
    
    ; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> master.lzxlinux.com @192.168.30.254
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 26944
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;master.lzxlinux.com.		IN	A
    
    ;; ANSWER SECTION:
    master.lzxlinux.com.	86400	IN	A	192.168.30.254
    
    ;; AUTHORITY SECTION:
    lzxlinux.com.		86400	IN	NS	slave.lzxlinux.com.
    lzxlinux.com.		86400	IN	NS	master.lzxlinux.com.
    
    ;; ADDITIONAL SECTION:
    slave.lzxlinux.com.	86400	IN	A	192.168.30.253
    
    ;; Query time: 0 msec
    ;; SERVER: 192.168.30.254#53(192.168.30.254)
    ;; WHEN: Mon Jun 03 13:49:39 CST 2019
    ;; MSG SIZE  rcvd: 114

解析成功。

整个DNS服务相关的部署没有问题，过程到此结束。

--------------------

更多资料参考：

[一篇文章让你了解DNS][DNS]

[www.centos.lzxlinux.com]: http://www.centos.lzxlinux.com
[DNS]: https://blog.51cto.com/13570193/2105393