# Reverse DNS

A [<mark style="color:blue;">reverse DNS (rDNS)</mark>](https://docs.ionos.com/cloud/support/general-information/glossary-of-terms#reverse-dns-rdns) maps a public IP address and a domain name. A reverse DNS lookup zone contains the attributes that instruct Cloud DNS to perform a Pointer (PTR) lookup against DNS servers to find the domain name mapped to the IPv4 or IPv6 addresses.

For more information about IPv6 configuration in the DCD, see [<mark style="color:blue;">IPv6 Configuration</mark>](/cloud/network-services/vdc-networking/ip-address/ipv6.md).

{% hint style="info" %}
**Prerequisites:**

* You need an IONOS Cloud account with API credentials configured with the appropriate permissions.
* You must be a contract administrator, owner, or a user with **Access and manage DNS** privilege to create and manage PTR records. You can also set User privileges via the [<mark style="color:blue;">API</mark>](/cloud/network-services/cloud-dns/api-how-tos/set-user-privileges-api.md).
* Before creating a Reverse DNS record, it is recommended to create an A or AAAA record for the IP address you want to use for the reverse DNS record. For more information, see [<mark style="color:blue;">Create a DNS Record</mark>](/cloud/network-services/cloud-dns/api-how-tos/create-dns-record.md).
* Sub-users can create Reverse DNS records for IPv4 addresses only if the user group they belong to has access to the concerned reserved IP block. For more information, see [<mark style="color:blue;">Add users to a group</mark>](/cloud/set-up-ionos-cloud/management/identity-access-management/user-management.md#add-users-to-a-group).
  {% endhint %}

{% hint style="warning" %}
**Note:**

* Reverse DNS lookup is supported "only" for the following:
  * Public IPv6 addresses assigned to your VDCs.
  * Reserved IPv4 addresses.
* The **IPv4 address** must be from a reserved IP range. To reserve an IPv4 address, follow these steps: 1. In the **DCD**, go to **Menu** > **Network Services** > **IP Management**. 2. Enter a name and the number of IPv4 addresses. 3. Select a region where you want your IPv4 addresses to be reserved. 4. Select **Reserve IP** to reserve the IPv4 address. 5. Select **OK** to confirm the reservation.
* For a reverse DNS record, you can use an **IPv6 address** that belongs to any of the **/56 IPv6** blocks assigned to the VDC and has a prefix length of **/128**. For example, consider the IPv6 address `2001:db8:1234:5678::1/128`, which belongs to a `2001:db8:1234:5678::/56` block. For more information, see [<mark style="color:blue;">IPv6 Configuration</mark>](/cloud/network-services/vdc-networking/ip-address/ipv6.md).
  {% endhint %}

## Quick Links

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><mark style="color:blue;"><strong>Create PTR Records for Reverse DNS</strong></mark></td><td>Learn how to create PTR records for reverse DNS.</td><td><a href="/pages/VAlSGhIdynvCBjxsPw5w">/pages/VAlSGhIdynvCBjxsPw5w</a></td></tr><tr><td><mark style="color:blue;"><strong>Update PTR Records</strong></mark></td><td>Learn how to update PTR records associated with reverse DNS.</td><td><a href="/pages/jDNubezJoQki7TuaEiBT">/pages/jDNubezJoQki7TuaEiBT</a></td></tr><tr><td><mark style="color:blue;"><strong>View PTR Records</strong></mark></td><td>Learn how to view the list of PTR records.</td><td><a href="/pages/jZASAURIyCVs2iAHC84b">/pages/jZASAURIyCVs2iAHC84b</a></td></tr><tr><td><mark style="color:blue;"><strong>Delete PTR records</strong></mark></td><td>Learn how to delete PTR records.</td><td><a href="/pages/tTBtJlA7T6GDrHCii7Xm">/pages/tTBtJlA7T6GDrHCii7Xm</a></td></tr></tbody></table>


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# Agent Instructions: Querying This Documentation

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Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ionos.com/cloud/network-services/cloud-dns/dcd-how-tos/reverse-dns.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.