It’s fairly obvious, giving a direct Yes or No answer won’t do for SEO-related questions like this. In this article, we will discuss domain names and URLs to fully understand whether they are case sensitive or not, and of course, if there are minor exceptions for specific cases.
Before getting deep into it, let’s get on some geek talk. The Domain Name System (DNS) is based on ASCII which is a character encoding standard for electronic communication. These domain names based on ASCII are built to be case insensitive, which means our regular domain names like Fiverr.com or Google.com are not case sensitive. It doesn’t matter whether you typing fiverr.com or FIVERR.com or Fiverr.com, your browser will take you to the same site.
This applies to most of the domain names we have today, again, it doesn’t matter whether it’s with a .com, .net, .org, or whatever they’re not originally built to be case sensitive.
It’s that simple, the answer is No, and they’re not case sensitive. However, things kind of break down when we are looking at URLs. An actual domain name might not be case sensitive, but the URL directing to a specific page on a site with the domain can be case sensitive.
Having a page called on a website called “info.htm” means the URL to it will be https://website.com/info.htm. This isn’t the same as https://website.com/INFO.htm or https://website.com/Info.htm. Using any of the last two will result in a 404 error. This happens because browsers and search engines can’t find the page; there’s no page called INFO.htm or Info.htm on the website.
URL case sensitivity may become an issue for SEO when multiple versions of a URL is seen by search engines. If you have shared links to the same page but with different cases, you will have a problem. Search engines will crawl the individual links leading to the page. While both will be ranked as actual links to your website, the one with the wrong case will lead to a 404 error. Hence, you will be sharing your SEO juice between two pages with one being inaccessible instead of having it all in one.
Domain names are generally not built to be case sensitive, however, there are cases where specific URLs of a website can be case sensitive. There is this recent, issue with Internationalized Domain Names (IDN). These new types of domain names can contain language-specific characters, as such, can potentially be case sensitive. However, this isn’t a problem right now as IDN registration isn’t a common practice.