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Domain Name Rules-Letter and Number wooden blocks image

Domain Name Rules: Can Domain Names Have Numbers? Symbols? Learn more!

Brett McKay
May 12, 2020 • 3 min read
(Updated on Sep 30, 2022)

Thousands of domains are registered across the internet daily, but the domain name rules, conventions and what you can and cannot register are often overlooked.  Can domain names have numbers? How about underscores or symbols? How come there are occasionally domain names with periods? We will be going over these questions and highlighting what you should consider when registering your domains.




Domain names can have numbers. Despite the ability to add them, numbers in domains are typically avoided as they can have a negative effect on how intuitive the domain name is to understand.

Having a name with numbers included may be a barrier for users accessing your website due to not understanding whether the domain name uses a digit character or a written word of a number (for example, “4” versus “four”).

Exceptions to this include terms where the number character is commonly used, such as B2B or MP4, which are understood and frequently written in those specific ways.

If you wanted to register a domain that has a more unclear numerical use, there is the option to register both versions of a domain (one using the word of the number and the other including just the single-digit character) and redirect the incorrect domain name to the proper domain name. Just ensure that both domain names are available before registering either domain.


Example: If your business name is “Metallic Seven”, you could try to register both and and redirect the latter to the former. This will minimize potential lost traffic opportunities.



Domains with hyphens are allowed, though they are rarer than including numbers. Much like how domain names can have numbers, domain names can have hyphens but they often have downsides. They are uncommon This is due to adding complexity and potentially a hurdle for your audience to land on your website.


Example: “Saying “One for All” and “One-for-All” out loud are two different things, and you are bound to lose some of your audience on their journey to find your website if hyphens are included. In almost all scenarios, it is best to forgo using hyphens and search for alternatives.”


Not Allowed



Periods cannot be used when registering a domain name. However, periods are included in websites that utilize subdomains, which is why some webpages have the following URL structure:


Subdomains are used to contain content that is separate from the main website but is still under the main website’s hosting.


Example: ‘’

blog. is a common subdomain for a website blog. The domain name does not include a period.


Symbols, Spaces or Underscores

Numbers and hyphens are the only symbols allowed in your domain name. Spaces and underscores are not allowed, and the symbols listed below are also not allowed.

! @ # $ % ^ & * ( ) ; : , ? / \ = + < >



Capital Letters

Domain names are case insensitive, which means using upper and lower case characters is irrelevant. Typing in a domain name in all capital letters will take you to the same domain as typing in all lowercase. You cannot register a domain that uses capital letters because of this, they are considered the same characters.


Domain Name Information to Keep in Mind

Character Limit

Domain names are only allowed to be 63 characters in length. The 63 characters do not include what is referred to as the ‘protocol identifier’ (https://) or the domain extension (such as .com or .org). This is purely the domain name (sometimes referred to as the ‘label’) between the two. Avoid having a domain name anywhere near this maximum length as it will become more challenging for users to find and navigate to your site.



Additional Domain Naming Considerations


Domain Name Length: Shorter domain names have the advantage of improving accessibility by typically being easier to type and remember.

Name Difficulty: Simpler domain names are often the best choice. They are much easier for users to type in, remember, and rely less on your audience’s spelling ability. 

Example: A language-learning website using ‘’ will be harder for users to get to due to using a more complex word to spell.


Avoid Branded Terms: Using trademarked or existing branded terms in a domain name can get you labelled as a cybersquatter, which is someone who registers a domain with a trademark to profit from or for malicious use.


Brandable vs. Description: Choosing between a new brand name idea or a descriptive name for your domain is an important decision as it can have a drastic effect on your domain’s discoverability. Be sure to read our blog going over the ins and outs of brandable versus descriptive domain names.


With this knowledge, you will be better equipped when registering a domain name by knowing what is and isn’t allowed, along with understanding how you can use characters such as numbers in a domain name if required. Knowing these guidelines can be useful, whether you are registering a domain for your business or even evaluating domains to invest in. 


Got an idea for registering a domain? Use Dynadot’s domain name search to register your domain in minutes.




Brett McKay
Marketing Associate

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