---
title: "rDNS Report"
description: "The Reverse DNS (rDNS) lookup is a process that converts an IP address back to its associated domain name."
url: https://helpcenter.smartlead.ai/en/articles/245-rdns-report
collection: "SmartDelivery"
updated: 2026-10-31
language: en
---

# rDNS Report

The Reverse DNS (rDNS) lookup is a process that converts an IP address back to its associated domain name.

![](https://staticfiles.gleap.io/ghelparticle/qeIuNob2ocks3A53y8sgvr7MIxtlLUa2GJx3I9eB69YPqzXZCPYCeUusipXbMk8igxitxsIxatd.png)

### rDNS (Reverse DNS)

The **Reverse DNS (rDNS)** lookup is a process that converts an IP address back to its associated domain name. Typically:

-   A standard **DNS** translates a domain name (e.g., [gmail.com](http://gmail.com)) into its IP address.
    
-   An **rDNS** does the opposite: it translates an IP address back to its domain, revealing where the email is originating from.
    

This process is crucial because email providers, like Gmail, check the **rDNS** of the sender to assess the legitimacy of the sending domain.

### Importance of IP Address and rDNS

The IP address and rDNS are critical for determining:

1.  If your emails are coming from a trusted infrastructure.
    
2.  Whether the originating IP is associated with spam or other negative indicators.
    

Although a blacklisted Gmail IP might show up in this section, it usually does not impact deliverability significantly due to the nature of **rotating Gmail IPs**.

## What is Google's Network and How Does rDNS Affect It?

Most of Google's network resolves to the domain [**1e100.net**](http://1e100.net). When emails are sent from Gmail, they originate from this domain, not from SmartLead's sending infrastructure. Here’s how it works:

-   **IP Address** ↔️ **Domain Name (**[**1e100.net**](http://1e100.net)**)** ↔️ **Gmail's Network**
    

If you see an rDNS resolving to [**1e100.net**](http://1e100.net), it indicates the email originated from a **Gmail IP address**. This is expected behavior and confirms that the Gmail infrastructure is sending your emails.

## Why Does the rDNS Vary?

You may notice discrepancies in the rDNS data, which can be due to:

-   **DNS Resolution Timing**: The point in time when the DNS query was made can affect the result.
    
-   **Network Caching**: DNS data may be cached differently across servers, causing slight variations.
    
-   **IP Origin Dynamics**: Google’s network includes many IPs, and their resolution paths can vary, but they all point back to Google's domain [**1e100.net**](http://1e100.net).