doc-exports/docs/dns/umn/dns_faq_031.html

How Can I Map the Private IP Address of an ECS to a Domain Name?

You can configure PTR records to allow end users to query domain names based on IP addresses.

To map the private IP address of an ECS to a domain name, you must create a private zone and add a PTR record to the zone.

To add a PTR record, you may refer to Creating a PTR Record.

The domain name for the PTR record must be in the x.x.x.x.in-addr.arpa format. in-addr.arpa is the domain name suffix used for reverse resolution.

For example, if the private IP address is 192.168.1.10, the domain name is 10.1.168.192.in-addr.arpa.

You need to create a private zone with the domain name set to 192.in-addr.arpa and add a PTR record with the Name field set to 10.1.168.

Creating a Private Zone

1. Log in to the management console.
2. In the service list, choose Network > Domain Name Service.

   The DNS console is displayed.

3. In the navigation pane on the left, choose Private Zones.

   The Private Zones page is displayed.

4. Click in the upper left corner and select the desired region and project.
5. Click Create Private Zone.
   Figure 1 Create Private Zone
   
6. Configure the parameters based on Table 1.

   Table 1 Parameters for creating a private zone

   Parameter	Description	Example Value
   Domain Name	Domain name you use to access the cloud servers or cloud services. Ensure that the domain name suffix is in-addr.arpa.	192.in-addr.arpa
   VPC	VPC to be associated with the private zone. Select the VPC you want to associate with the private zone.	N/A
   Email	(Optional) Email address of the administrator managing the private zone. Recommended email address: HOSTMASTER@Domain name For more information about the email address, see Why Was the Email Address Format Changed in the SOA Record?	HOSTMASTER@example.com
   Tag	(Optional) Identifier of a resource Each tag contains a key and a value. You can add a maximum of 20 tags to a zone. For details about tag key and value requirements, see Table 2.	example_key1 example_value1
   Description	(Optional) Supplementary information about the zone You can enter a maximum of 255 characters.	This is a private zone.

   Table 2 Tag key and value requirements

   Parameter	Requirements	Example Value
   Key	Cannot be left blank. Must be unique for each resource. Can contain a maximum of 36 characters. Can contain only letters, digits, hyphens (-), at signs (@), and underscores (_).	example_key1
   Value	Cannot be left blank. Can contain a maximum of 43 characters. Can contain only letters, digits, hyphens (-), at signs (@), and underscores (_).	example_value1

7. Click OK.
8. Switch back to the Private Zones page.
   You can view the created private zone in the private zone list.

   

   Click the domain name to view SOA and NS record sets automatically generated for the zone.

   • The start of authority (SOA) record includes administrative information about your zone, as defined by the Domain Name System (DNS).
   • The NS record set defines the authoritative DNS servers for the domain name.

Adding a PTR Record

1. On the Private Zones page, click the domain name of the private zone you created.

   The Record Sets page is displayed.

2. Click Add Record Set.

   The Add Record Set dialog box is displayed.

   Figure 2 Add Record Set
   
3. Configure the parameters based on Table 3.

   Table 3 Parameters for adding a PTR record

   Parameter	Description	Example Value
   Name	Part of the private IP address in reverse order.	10.1.168 For example, if the IP address is 192.168.1.10, the domain name in the PTR record must be 10.1.168.192.in-addr.arpa. If the domain name is 192.in-addr.arpa, enter 10.1.168. If the domain name is 1.168.192.in-addr.arpa, enter 10.
   Type	Type of the record set.	PTR – Map IP addresses to domains
   TTL (s)	Cache duration of the record set, in seconds.	Default value: 300
   Value	Domain name mapped to the IP address. You can enter only one name.	mail.example.com
   Tag	(Optional) Identifier of a resource Each tag contains a key and a value. You can add a maximum of 20 tags to a record set. For details about tag key and value requirements, see Table 2.	example_key1 example_value1
   Description	(Optional) Supplementary information about the PTR record.	The PTR record is for reverse resolution.

4. Click OK.
5. Switch back to the Record Sets tab.

   The added record set is in the Normal state.

Parent topic: Private Zones