What is DNS? To better understand your hosting environment, you need to bring yourself up to speed with various aspects…
Reverse DNS is one of those obscure things that you only seem to learn about when you become a pro at managing your website.
First you learn about web hosting and why it’s impossible to start a website without it, then you learn the importance of backing up your website so that all your hard work doesn’t vanish overnight, and then years later, when you’ve been successfully managing your website for a while, you somehow encounter the term “reverse DNS”, and a whole new world of possibilities opens up for you.
Well, today, we’re giving your internet knowledgebase a massive boost. We’re diving right into DNS.
Let’s begin, shall we?
Before we can get into reverse DNS, we have to wrap our minds around DNS.
DNS stands for Domain Name System, and it’s a list of every website’s domain name and corresponding IP address.
A website’s domain name will typically look like “www.websitenamehere.com”, but its computer-readable IP address will look more like “111.122.00.01”. The domain name is easier for you to remember than the IP address, but your computer needs to know a website’s IP address before it can load the website in your browser.
So, you can think of the DNS as a kind of phonebook, but for IP addresses. It lists websites by their domain name and shows their IP address.
(By the way, every server has an IP address. If you’re connected to the internet, your device has an IP address, even if you don’t have a website.)
Let’s say that for some reason, you have a burning desire to visit www.websitenamehere.com. You type it into your browser, and your browser loads the page. But behind the scenes, your computer is performing a DNS lookup. (Since we’re going to compare it to a reverse DNS lookup, we can also call a DNS lookup by its more specific name: forward DNS lookup.)
What happens when you type a website into your browser is this: You enter the website into the browser, but your computer still needs to know the IP address before it can load the website. So, it forwards your domain name request to a DNS server that returns the corresponding IP address. Now that your browser knows the website’s IP address, it can load the page.
A reverse DNS lookup works the other way around: It’s the process of querying the DNS to figure out a domain name when you already have the IP address.
Reverse DNS is mostly used for tracking where web traffic and emails come from. Many email servers are configured to reject emails from any IP address that doesn’t have reverse DNS. (More on that later!)
And that’s not the only reason you need reverse DNS.
If you have a website, you’ll have a list of all the IP addresses that have visited your website. When you perform a reverse DNS lookup, you can find the corresponding domain names of everyone who’s visited your website.
This can give you valuable information about where to focus your marketing efforts, who your demographic is, and where most of your web traffic comes from.
Reverse DNS can help keep your website safe from email spammers and bad server neighbours, and it can even help you make better marketing decisions and scope out your competitors. This powerful tool is definitely worth knowing about!