# Set reverse DNS for your server

> What reverse DNS (PTR) records are, when you need one, how to set one in the panel or with rack4, and how to check it with dig.

Source: https://rack4.io/help/reverse-dns · Updated: 2026-10-21

To set reverse DNS (a PTR record) for your server, create the name's `A` record at your DNS host first, then open the server's **Reverse DNS** tab in the panel, type the name and press **set reverse dns**. Reverse DNS turns an address back into a name, `203.0.113.42` to `mail.example.com`; the address is ours, so the record is set through Rack4 rather than at your DNS host.

## What you need

- A domain name whose DNS you can edit.
- The server's addresses, from the top of its page in the panel.
- Ten minutes, plus up to a working day for the record to go live.

## When you need it

You need it if you send email from the server. Plenty of mail servers reject or junk mail from an address with no reverse DNS, or whose reverse name doesn't point back to the same address. Set it before you send anything, and read [Sending email: port 25](https://rack4.io/help/open-port-25) too.

It's also nice in logs and `traceroute` output, where a name is easier to recognise than a number. For a plain web server, though, you can skip it.

## Create the forward record first

The reverse record should match a forward one, so start there ([point a domain at your VPS](https://rack4.io/tutorials/point-a-domain-to-your-vps) walks through it). At your DNS provider:

```text
mail.example.com.  A     203.0.113.42
mail.example.com.  AAAA  2001:db8:9::2
```

Check it from your computer:

```bash
dig +short mail.example.com A
```

It has to return your server's address before you go on.

## Set the reverse record

1. In the panel, open the server and choose the **Reverse DNS** tab.
2. Find the box for the address: one for IPv4, and one for IPv6 if the server has it.
3. Type the name in **hostname**, like `mail.example.com`, and press **set reverse dns**.

[Screenshot: The Reverse DNS tab of api-eu-1.northwind-labs.example: the IPv4 box with its address, the name api-eu-1.northwind-labs.example, the state live, the hostname field, the set reverse dns button and the clear link] Each box shows the name now set and its state: requested, live, being removed or failed.

With the [rack4 CLI](https://rack4.io/help/install-the-rack4-cli), it's one command per address:

```bash
rack4 rdns web-1 set 203.0.113.42 mail.example.com
rack4 rdns web-1 set 2001:db8:9::2 mail.example.com
```

Before we accept the name, we look it up and check that it points to that address: the `A` record for the IPv4 address, `AAAA` for IPv6. If the name has no such record, points somewhere else, or doesn't answer within 3 seconds, you get a message saying which, and nothing changes. Fix the forward record, give it a minute, and try again.

Reverse records are set by hand for now. A request shows as **requested, waiting to be set** until it's done, usually within a working day, and then as **live**. To take a name off, press **clear** in the panel or run `rack4 rdns web-1 rm 203.0.113.42`. It shows as **being removed** until we've reset it.

You get ten tries an hour across your account. Clears count, and so do tries the forward check refuses. When you delete a server, we reset its reverse DNS before its addresses go to anyone else.

## Check it

```bash
dig +short -x 203.0.113.42
dig +short -x 2001:db8:9::2
```

Once the panel says **live**, each should print `mail.example.com.`, trailing dot included. Resolvers can hang on to the old answer for up to the record's TTL.

Then close the loop:

```bash
dig +short mail.example.com A
```

That should give back the same address you started with. Mail servers call this forward-confirmed reverse DNS, and it's what they actually check.

## Troubleshooting

- **The name is refused because it doesn't point to the address.** The forward check found no `A` (or `AAAA`) record, or one with another address, or no answer within 3 seconds. Fix the record at your DNS host, wait a minute, and try again.
- **`dig -x` still shows nothing or the old name.** Your resolver has it cached; wait out the TTL.
- **The reverse name doesn't resolve back.** The forward `A` or `AAAA` record is the one to fix.
- **Still waiting after a working day, or failed.** [Open a support ticket](https://my.rack4.io/support/new?category=network) with the address.

## Next steps

- [Sending email: port 25](https://rack4.io/help/open-port-25)
- [Check that IPv6 works](https://rack4.io/help/ipv6-setup)
- [The server overview page](https://rack4.io/help/server-overview)

## Doing it on Rack4

Reverse DNS is free on every [plan](https://rack4.io/plans), for the main IPv4 and IPv6 addresses.