# Set reverse DNS
Source: https://docs.infraista.com/en/networking/floating-ips/set-reverse-dns



Reverse DNS (a PTR record) is the hostname others see when they look up your IP address. Mail servers
check it, so set it on any address you send email from.

**Before you start:** point an A record for the hostname at the address first. Mail servers may reject
mail when the two don't match. Reverse DNS for IPv6 addresses isn't available yet.

1. Open the floating IP and find **Reverse DNS**.
2. Select **Edit** and enter the **Hostname**, for example `mail.northwind.example`.
3. Select **Save**.

<Shot name="networking/floating-ips/rdns" alt="The Reverse DNS card with the hostname field" />

Lookups show the new name within 5 minutes. **Use default** goes back to the original name.

## Related [#related]

* [MailGate](/en/email/mailgate)