# 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>](https://docs.ionos.com/sections-test/guides/network-services/vdc-networking/ip-address/ipv6).

{% 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>](https://docs.ionos.com/sections-test/guides/network-services/cloud-dns/api-how-tos/set-user-privileges-api).
* 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>](https://docs.ionos.com/sections-test/guides/network-services/cloud-dns/api-how-tos/create-dns-record).
* 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>](https://docs.ionos.com/sections-test/guides/set-up-ionos-cloud/management/identity-access-management/user-management#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>](https://docs.ionos.com/sections-test/guides/network-services/vdc-networking/ip-address/ipv6).
  {% 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="reverse-dns/create-ptr-record">create-ptr-record</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="reverse-dns/update-ptr-record">update-ptr-record</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="reverse-dns/view-ptr-records">view-ptr-records</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="reverse-dns/delete-ptr-record">delete-ptr-record</a></td></tr></tbody></table>