开启/关闭 PTR 记录
更新时间：2023-11-06 09:26:48
文档背景
DNS 服务器里面有两个区域，即"`正向查找区域`"和"`反向查找区域`"，正向查找区域就是通常所说的域名解析，反向查找区域即是 IP 反向解析，它得到作用是通过查找 IP 地址的 PTR 记录来得到该 IP 地址指向的域名。要成功得到域名就必须有该 IP 地址的 PTR 记录。PTR 及记录是邮件交换记录的一种，邮件交换记录中有 A 记录和 PTR 记录，A 记录解析名字到地址，PTR 记录解析地址到名字。
VPC 网络内网 DNS 服务功能可以对 VPC 内部提供域名解析的服务，可以开启/关闭内网 DNS 服务。同时支持开启/关闭 PTR 解析类型-反向 DNS 解析。
路径：网络-VPC网络-管理配置-DNS服务
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示例场景
以下以设置域名 aa.localdomain 解析到 192.168.8.2 为例
开启 PTR 记录后，测试结果如下：
[root@i-0026uq32 ~]# ping aa
PING aa.localdomain (192.168.8.2) 56(84) bytes of data.
64 bytes from aa.localdomain (192.168.8.2): icmp_seq=1 ttl=64 time=0.014 ms
64 bytes from aa.localdomain (192.168.8.2): icmp_seq=2 ttl=64 time=0.041 ms
^C
--- aa.localdomain ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.014/0.027/0.041/0.014 ms通过 dig 测试域名解析和 PTR 反向解析记录：
[root@i-0026uq32 ~]# dig aa.localdomain
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.5 <<>> aa.localdomain
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19091
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;aa.localdomain. IN A
;; ANSWER SECTION:
aa.localdomain. 604800 IN A 192.168.8.2
;; AUTHORITY SECTION:
localdomain. 604800 IN NS localhost.localdomain.
;; ADDITIONAL SECTION:
localhost.localdomain. 604800 IN A 127.0.0.1
;; Query time: 0 msec
;; SERVER: 192.168.255.254#53(192.168.255.254)
;; WHEN: Tue May 18 14:08:58 CST 2021
;; MSG SIZE rcvd: 99[root@i-0026uq32 ~]# dig -x 192.168.8.2
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.5 <<>> -x 192.168.8.2
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28577
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 3
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;2.8.168.192.in-addr.arpa. IN PTR
;; ANSWER SECTION:
2.8.168.192.in-addr.arpa. 604800 IN PTR aa.localdomain.
;; AUTHORITY SECTION:
168.192.in-addr.arpa. 604800 IN NS localhost.
;; ADDITIONAL SECTION:
localhost. 604800 IN A 127.0.0.1
localhost. 604800 IN AAAA ::1
;; Query time: 0 msec
;; SERVER: 192.168.255.254#53(192.168.255.254)
;; WHEN: Tue May 18 14:08:17 CST 2021
;; MSG SIZE rcvd: 148关闭 PTR 记录，测试结果如下：
[root@i-ets7af6q ~]# dig -x 192.168.8.2
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> -x 192.168.8.2
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 26375
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;2.8.168.192.in-addr.arpa. IN PTR
;; AUTHORITY SECTION:
168.192.in-addr.arpa. 85914 IN SOA 168.192.in-addr.arpa. . 0 28800 7200 604800 86400
;; Query time: 8 msec
;; SERVER: 114.114.114.114#53(114.114.114.114)
;; WHEN: Tue May 18 15:34:27 CST 2021
;; MSG SIZE rcvd: 88