DNS区域传送、子域授权

前言

DNS服务器搭建参考上一篇；
DNS主从复制，就是将主DNS服务器的解析库复制传送至从DNS服务器，进而从服务器就可以进行正向、反向解析了。从服务器向主服务器更新查询数据，保证数据一致性，此为区域传送。也可以说，DNS区域传送，就是DNS主从复制的实现方法，DNS主从复制是DNS区域传送的表现形式。
DNS区域传送的两种方式：

• zxfr:完全区域传送
• ixfr:增量区域传送

当一个新的DNS服务器添加到区域中并配置为从DNS服务器时，它则会执行完全区域传送，在主DNS服务器上获取完整的资源记录副本；同时为了保证数据同步，主域名服务器有更新时也会及时通知辅助域名服务器从而进行更新（增量区域传送）。

区域传送

主服务器：192.168.2.72
从服务器： 192.168.2.104
两台服务器都提前安装好named服务

完全区域传送

1.对主服务器/etc/named.conf配置进行修改，在options配置段内增加：

notify yes;

2.在主服务器上正向、反向文件中增加从服务器的NS记录
正向区域

@       NS      dns2
dns2    A       192.168.2.104

反向区域

IN      NS      dns2.magedu.com.
104      IN      PTR     dns2.magedu.com.

3.复制主服务器上配置文件至从服务器

#scp 192.168.1.72:/etc/named.rfc1912.zones /etc/

#scp 192.168.1.72:/etc/named.conf /etc/

4.修改从服务器上/etc/named.rfc1912.zones

zone "magedu.com" IN {
        type slave;
        masters { 192.168.2.72; };
        file "magedu.com.zone";
};

zone "2.168.192.in-addr.arpa" IN {
        type slave;
        masters { 192.168.2.72; };
        file "2.168.192.zone";
};

5.启动从服务器DNS服务，查看日志，及/var/named/目录下是否已同步成功主服务器区域文件

增量区域传送

1.修改主服务器正向解析文件，增加一条A记录，将序列号加1后保存退出
2.reload主DNS服务器，查看日志
主服务器日志：

Jan 20 02:12:55 agent named[35582]: zone 2.168.192.in-addr.arpa/IN: sending notifies (serial 2019011301)
Jan 20 02:12:55 agent named[35582]: client 192.168.2.104#39669 (magedu.com): transfer of 'magedu.com/IN': AXFR-style IXFR started
Jan 20 02:12:55 agent named[35582]: client 192.168.2.104#39669 (magedu.com): transfer of 'magedu.com/IN': AXFR-style IXFR ended
Jan 20 02:12:56 agent named[35582]: client 192.168.2.104#34346: received notify for zone 'magedu.com'

从服务器日志：

Jan 20 03:02:25 zabbix named[100773]: client 192.168.2.72#60290: received notify for zone 'magedu.com'
Jan 20 03:02:25 zabbix named[100773]: zone magedu.com/IN: Transfer started.
Jan 20 03:02:25 zabbix named[100773]: transfer of 'magedu.com/IN' from 192.168.2.72#53: connected using 192.168.2.104#39669
Jan 20 03:02:25 zabbix named[100773]: zone magedu.com/IN: transferred serial 2019012001
Jan 20 03:02:25 zabbix named[100773]: transfer of 'magedu.com/IN' from 192.168.2.72#53: Transfer completed: 1 messages, 10 records, 268 bytes, 0.001 secs (268000 bytes/sec)
Jan 20 03:02:25 zabbix named[100773]: zone magedu.com/IN: sending notifies (serial 2019012001)
Jan 20 03:02:25 zabbix named[100773]: client 192.168.2.72#4595: received notify for zone '2.168.192.in-addr.arpa'
Jan 20 03:02:25 zabbix named[100773]: zone 2.168.192.in-addr.arpa/IN: notify from 192.168.2.72#4595: zone is up to date

3.在反向解析文件增加一条PTR记录，同样序列号加1
主DNS服务器日志：

Jan 20 02:17:44 agent named[35582]: zone 2.168.192.in-addr.arpa/IN: sending notifies (serial 2019012001)
Jan 20 02:17:44 agent named[35582]: client 192.168.2.104#57041 (2.168.192.in-addr.arpa): transfer of '2.168.192.in-addr.arpa/IN': AXFR-style IXFR started
Jan 20 02:17:44 agent named[35582]: client 192.168.2.104#57041 (2.168.192.in-addr.arpa): transfer of '2.168.192.in-addr.arpa/IN': AXFR-style IXFR ended

从DNS服务器日志：

Jan 20 03:07:38 zabbix named[100773]: client 192.168.2.72#17270: received notify for zone '2.168.192.in-addr.arpa'
Jan 20 03:07:38 zabbix named[100773]: zone 2.168.192.in-addr.arpa/IN: Transfer started.
Jan 20 03:07:38 zabbix named[100773]: transfer of '2.168.192.in-addr.arpa/IN' from 192.168.2.72#53: connected using 192.168.2.104#57041
Jan 20 03:07:38 zabbix named[100773]: zone 2.168.192.in-addr.arpa/IN: transferred serial 2019012001
Jan 20 03:07:38 zabbix named[100773]: transfer of '2.168.192.in-addr.arpa/IN' from 192.168.2.72#53: Transfer completed: 1 messages, 8 records, 242 bytes, 0.001 secs (242000 bytes/sec)
Jan 20 03:07:38 zabbix named[100773]: zone 2.168.192.in-addr.arpa/IN: sending notifies (serial 2019012001)

4.通过dig命令验证

root@node2:~# dig -t A ftp.magedu.com @192.168.2.104

; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> -t A ftp.magedu.com @192.168.2.104
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2878
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;ftp.magedu.com.			IN	A

;; ANSWER SECTION:
ftp.magedu.com.		600	IN	A	192.168.2.1

;; AUTHORITY SECTION:
magedu.com.		600	IN	NS	dns2.magedu.com.
magedu.com.		600	IN	NS	dns1.magedu.com.

;; ADDITIONAL SECTION:
dns1.magedu.com.	600	IN	A	192.168.2.72
dns2.magedu.com.	600	IN	A	192.168.2.104

;; Query time: 5 msec
;; SERVER: 192.168.2.104#53(192.168.2.104)
;; WHEN: Sun Jan 20 15:19:47 CST 2019
;; MSG SIZE  rcvd: 129

测试通过从服务器反向解析

root@node2:~# dig -x 192.168.2.1  @192.168.2.104

; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> -x 192.168.2.1 @192.168.2.104
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14837
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;1.2.168.192.in-addr.arpa.	IN	PTR

;; ANSWER SECTION:
1.2.168.192.in-addr.arpa. 600	IN	PTR	ftp.magedu.com.

;; AUTHORITY SECTION:
2.168.192.in-addr.arpa.	600	IN	NS	dns1.magedu.com.
2.168.192.in-addr.arpa.	600	IN	NS	dns2.magedu.com.

;; ADDITIONAL SECTION:
dns1.magedu.com.	600	IN	A	192.168.2.72
dns2.magedu.com.	600	IN	A	192.168.2.104

;; Query time: 2 msec
;; SERVER: 192.168.2.104#53(192.168.2.104)
;; WHEN: Sun Jan 20 15:24:38 CST 2019
;; MSG SIZE  rcvd: 151

DNS子域授权

当一个域很大时，而且还有上下层关系，如果所有的记录变更都由某一台服务来管理的话会很不方便。因此DNS也会域和子域，上层DNS可以将子域的管理授权给子域中的NDS服务器来管理记录的变更，这种做法叫子域授权。

子域授权配置

规划如下：
父域为：magedu.com
NS地址：ns1.magedu.com
子域为：dev.magedu.com
NS地址为：ns1.dev.magedu.com

父域服务器配置

只需在区域解析库文件中添加下层DNS服务器的NS与A记录即可

dev.magedu.com. NS      dns1.dev.magedu.com.
dns1.dev.magedu.com.    A       192.168.2.165

子域服务器配置

子域需要有完整的区域相关配置
在/etc/named.rfc1912.zones中加入子域定义

zone "dev.magedu.com" IN {
        type master;
        file "dev.magedu.com.zone";
};

创建dev.magedu.com.zone区域解析文件

$TTL 600
@       IN      SOA     dns1.dev.magedu.com.    admin.dev.magedu.com. (
                2019012002;
                2H;
                15M;
                1W;
                1D);
@       IN      NS      dns1
dns1    IN      A       192.168.2.165
www     IN      A       192.168.2.18

在子域DNS服务器添加指向父域的转发器

//将查询父域的请求转发给父域DNS
zone "magedu.com" IN {
        type forward;
        forward only;
        forwarders { 192.168.2.72; };
};

配置完成重启服务。
通过dig命令测试解析结果：

通过子域解析 www.dev.magedu.com

root@node2:~# dig -t A www.dev.magedu.com @192.168.2.165

; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> -t A www.dev.magedu.com @192.168.2.165
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36922
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.dev.magedu.com.		IN	A

;; ANSWER SECTION:
www.dev.magedu.com.	600	IN	A	192.168.2.18

;; AUTHORITY SECTION:
dev.magedu.com.		600	IN	NS	dns1.dev.magedu.com.

;; ADDITIONAL SECTION:
dns1.dev.magedu.com.	600	IN	A	192.168.2.165

;; Query time: 17 msec
;; SERVER: 192.168.2.165#53(192.168.2.165)
;; WHEN: Sun Jan 20 16:09:31 CST

通过父域解析 www.dev.magedu.com

root@node2:~# dig -t A www.dev.magedu.com @192.168.2.72

; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> -t A www.dev.magedu.com @192.168.2.72
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61135
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.dev.magedu.com.		IN	A

;; ANSWER SECTION:
www.dev.magedu.com.	600	IN	A	192.168.2.18

;; AUTHORITY SECTION:
dev.magedu.com.		600	IN	NS	dns1.dev.magedu.com.

;; Query time: 318 msec
;; SERVER: 192.168.2.72#53(192.168.2.72)
;; WHEN: Sun Jan 20 16:19:13 CST 2019
;; MSG SIZE  rcvd: 82

通过子域DNS服务器解析父域的A记录

root@node2:~# dig -t A www.magedu.com @192.168.2.165

; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> -t A www.magedu.com @192.168.2.165
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47969
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 13, ADDITIONAL: 27

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.magedu.com.			IN	A

;; ANSWER SECTION:
www.magedu.com.		301	IN	CNAME	web.magedu.com.
web.magedu.com.		301	IN	A	192.168.2.21


;; Query time: 2 msec
;; SERVER: 192.168.2.165#53(192.168.2.165)
;; WHEN: Sun Jan 20 16:21:30 CST 2019
;; MSG SIZE  rcvd: 873