Can a domain name have an underscore (_)?

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Domain names are essential when you must translate a name to a server IP address that locates the host of your web application’s resources.

Instead of typing a lengthy IP address such as on your browser to access a website, Domain Name System (DNS) has enabled us to associate such a lengthy IP address to a simple name such as

So, instead of your users or you typing the long IP address, you only need to know, type it in the browser, and


you are able to access the website and other resources located on the server (

What does this relate to domain names and underscores?

Well, for you to be able to register and own a valid domain name, you must follow the rules specified by the domain naming system (DNS).

For now, you are thinking of adding an underscore because the keywords you want to have in your domain name are not available.

And because of that… I want to tell you…

A domain name cannot have an underscore. According to the rules and specifications of the DNS and RFC, you cannot register a domain name with an underscore in any part of the domain name, whether at the start or end of the domain name.

So, is an invalid domain name.

Why a domain name cannot have an underscore

A domain name cannot have an underscore for these reasons:

The RFC 1035 code and ICANN prohibit the user underscores in a domain name.

It only allows the use of alphanumeric characters such as letters A to Z, and numbers 0 to 9.

Besides, a domain name can have fada characters that have acute accents.


Prohibiting domain names from having underscores is a great way to enhance readability and memorability.

A domain name with a couple of underscores or a mixture of underscores and dashes can be very confusing for users accessing your website.

If a domain was to have multiple underscores, it would be very hard to memorize and remember where to put each underscore in the domain name.


Domain names are universally recognizable as having letters, numbers, or an underscore.

Having a domain name that follows these standards helps maintain a consistent naming structure.

So, if you desired your domain name to have an underscore, here are a couple of things that you can do as alternatives:

  1. Replace the underscore with a dash to make it a valid domain name (although not recommended to have a dash in your domain name)
  2. The recommended approach is to be creative with your name and come up with a brandable, simple, and memorable domain name. You can follow this guide that shows you how to create simple but creative domain names.

What characters are allowed in a domain name?

Other than letters (a-z), digits (0-9), and hyphens (-), a domain name is allowed to have fada characters that have acute accents such as á, é, í, ó, and ú.

fada / long accent characters

Fada characters are accented characters that are used to modify the pronunciation of a base letter such as A, E, I, O, and U.

Examples of fada characters are the long vowels á, é, í, ó, ú.

These accented characters are also accepted in a domain name.

Here is an example page showing a domain name with fada characters á, é, í, and ó characters that is available on Namecheap registrar.

Domain name with fada characters

Quick one!

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Hyphen (-)

Another character that is accepted in a domain name is the hyphen. You can use a single hyphen to separate letters, numbers, or words in a domain name.

However, you cannot use two or more hyphens consecutively in a domain name.

You can read more about using dashes in a domain name here.

… and that’s it!

What to read next?

Does a domain name cost per year

See ya!

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Badi here, creator of— A website dedicated to providing helpful information and how-to's of web development and hosting. Inspired by a fascination to write the most efficient code to make a computer laugh, & humans, Steve has a passion for organizing characters to create code and informative content.
What makes me happy?
Well, nothing like the feeling of finally figuring out that one pesky bug that's been driving me crazy.

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