Trang chủ SEO Basic What are subdomains? All the knowledge about subdomains you need to know

What are subdomains? All the knowledge about subdomains you need to know

bởi Nguyễn Thành Tiến

Subdomain is a familiar concept for website administrators. However, for those who are new to the website, it is still not clear what a subdomain is , how to use and create subdomains for optimal. This article will help you better understand the subdomain as well as its role in the Internet.

What are subdomains? Overview of knowledge about subdomains to know

General knowledge about subdomains

What are subdomains?

A subdomain , also known as a subdomain, is a part separated from the main domain (domain name), operating separately as a normal website and having the same main domain name. Therefore, in terms of SEO, it is not affected by any backlinks from the main domain.

I will take an example to make it easier to visualize. Your website has a domain of . You want to create a blog site to provide information. You can then register a subdomain of the form

What are subdomains?

What is the concept of subdomains?

With a subdomain, you can completely create a separate and independent website without buying a new domain name or creating an additional Module that works under the control of the main domain.

Subdomains are often used for websites specializing in e-commerce, blogs or reviews,…

What are subdomains?

>> See also: What is a domain ? Distinguish domain and subdomain

Purpose of use of subdomain

Although the subdomain is part of the main website, Google still considers it an independent entity. It can be said that the birth of a subdomain is an extremely useful key for users.

Businesses in general and administrators in particular can use subdomains for many different purposes.

Subdomain or subfolder better for SEO?

In the Video, Google’s John Mueller explained:
You’ll need to verify subdomains separately in Search Console, make any changes to settings, and monitor overall performance on each subdomain.

We had to learn how to crawl them separately, but for the most part it was just a formality for the first few days.

Create a website specifically for a certain audience

The main purpose of a subdomain is to create a new website while keeping the old domain name . It will not cost you any more to register a domain name but still create a website that acts as a main website with a subdomain.

Subdomains will be really useful if you want to create a place full of information to serve a specific audience with appropriate content and language.

Creating multiple websites is much easier than maintaining a multilingual website.

With a subdomain, you can create a new and unique website

You can create a separate website with subdomain

Example: A fashion company wants to create a website for men’s clothing, a website for women’s clothing, and a website for children’s wear. This is simple when there is a supporting subdomain. Creating a website with images and languages ​​suitable for each customer will help you increase conversion rates and revenue for your business.

Separate your blog or e-commerce site from your main website

For a multi-industry business, using subdomains to separate the Modules on the main website into independent websites will be beneficial for scale development.

For example: Your company trades in a variety of items such as clothes, shoes, cosmetics, etc. You want to develop a blog for each product group, you cannot combine them all on one Module. Therefore, you can use subdomains to separate them for each website. Because managing many independent websites will be easier than managing a multi-site website.

Create a mobile-specific website

Use subdomains to provide the best user experience when using mobile devices. However, this method is no longer commonly used. Because now, websites are designed with Responsive standards, mobile standards.

Therefore, subdomains are used to design non-mobile websites . Instead of having to align content to fit the screen size, your website can determine the device type and provide the appropriate layout.

You can use subdomains to create mobile-specific websites

Subdomain supports creating mobile-specific websites

For example: A user accessing the website using a computer (PC) will return the result However, when accessing by phone, it will return a subdomain

Cost savings

When using a subdomain, you absolutely do not have to pay any more . Because you paid to buy the domain name before. Therefore, you do not need to buy an additional domain name, but you can still create many independent websites.

Besides, you can take advantage of the web design interface managed by the subdomain without worrying about duplication or additional costs. This helps you save on website design costs and still bring high efficiency.

When to use Subdomain to be effective?

Subdomains are free and endless resources so you can use them at any time. However, they will be effective if used for the right purpose. Below, I will answer for you exactly when to use subdomains.

The company launches a new product or service

When a business launches a new product or service for a customer group that is not the same as the customer group on the main website.

At this point, your task is to use the subdomain to create a new website for this customer group . Website will have separate content and design.

Subdomain is also a tool to help businesses create new campaigns or test content. After creating your website, you can advertise to see if the campaign is working.

If it works well then you can build this website. If not, you just need to delete this subdomain. This process will not cause any loss.

Management and maximum support of websites

Your business may have a large team of administrators to manage a multi-disciplinary website well. However, this will be difficult to have specific processes and may cause overlapping of tasks.

Therefore, businesses need to separate each product group into separate websites with corresponding subdomains and assign them to administrators. At this point, the management will become easier and better controlled.

In particular, for e-commerce sites, the security is more thorough than blogs or review sites. Therefore, only when separating them, the security will maximize its use.

Promotion and branding

Creating a product launch website with the support of a subdomain will help businesses both reach customers quickly and launch effective advertising campaigns.

In addition, businesses can take advantage of traffic from the main domain to make SEO more effective. Only with the right and appropriate campaigns can businesses build brands quickly and sustainably.

How many subdomains can a main domain create?

As a rule, creating subdomains from the main domain is unlimited in number. One primary domain can create an infinite number of subdomains.

Therefore, a lot of people have used this way to make money. The way to make money is also quite simple. You only need to spend some money to buy a “genuine” domain. Then create related subdomains and sell to those in need.

However, when creating a website under the support of a subdomain depends on the following factors:

  • The configuration that the main website registers as a server
  • Configure the DNS server of the hosting domain and resolve the bandwidth of the DNS server provider
  • SEO Compatibility

One of the important factors that make webmasters limit subdomains is SEO compatibility. The more subdomains created, the less SEO compatibility there is. This will greatly affect the main website.

Domain and subdomain are not too different. Therefore, many people are still confused and think that “www” is part of the domain.

However, the domain is only of the form “” , and “” is a subdomain. Because it is so familiar, many people are still confused. You can replace “www” with another subdomain like or,…

It is easy to confuse the two concepts of domain and subdomain

Domains and subdomains are very confusing

Notes about subdomains

In fact, besides the advantages, subdomains also have disadvantages. Therefore, when using subdomains, you need to keep the following in mind:

Tightly manage subdomains to avoid being spoofed

The disadvantage of creating too many subdomains is selling or transferring the website to someone else. If one of the subdomains is spammed or prosecuted, the remaining subdomains are also at risk of being affected.

Even, if it is detected that your subdomain is fake, the main domain will be permanently deleted. Unless you can provide proof that you are not profiteering, these procedures are cumbersome.

Subdomain requires more admin to build

When there are many new websites created, the construction and administration work also becomes more. Although you can manage the websites independently, the administrator’s workload will double. If only using a subdomain to create a support website, the job is simpler.

Difficult to create consistency across websites

In order for the websites created from the subdomain to be consistent with the main website, the business will have to use that design. However, it will be difficult if you maintain consistency on a brand new website without the support of professional web design units.

Subdomain affects SEO

Previously, Google considered the main domain and subdomain as two independent websites. Therefore, SEO administrators have taken advantage of this to improve SEO rankings. However, Google’s algorithm has now changed, domains and subdomains are ranked almost the same.

The more subdomains, the more influence on the ranking of the main website. This is shown by the fact that when you search for keywords, the main domain is displayed more than the subdomain.

Should the website use subdomains or subdirectories?

Frequently asked questions about Subdomains

How many subdomains can a main domain create?

As a rule, creating subdomains from the main domain is unlimited in number. A primary domain can create an infinite number of subdomains. The more subdomains created, the less SEO compatibility there is. This will greatly affect the main website.

Are subdomains separate websites?

Google ranks similar subdomains to subdirectories. But there is one key difference, which is that subdomains are considered independent websites and are distinct from the main domain.

Can subdomains rank on Google?

This is a common question regarding subdomains and SEO. The problem is not whether the subdomain will rank on Google, but how. There are big implications for SEO considering that subdomains rank separately from the main site.

Should I use a subdomain for my blog?

When it comes to blog hosting, subdomains are bad for SEO. Putting your blog on a subdomain will create more work for your business and disrupt your SEO strategy. Instead of optimizing one website, you will have to optimize 2 websites.

What is the difference between subdomain and subdirectory?

The subdomain divides the site so you can set up specific content types that are different from the main domain. A subdirectory is a path in the website . A subdirectory is one level in the domain’s hierarchy. The subdirectories branch from the subdomain they belong to the main domain..

Are subdomains indexed?

Google will index subdomains if you link to them from your main domain, but if your site is new, it will take time for Google to index everything. Simply put, a subdomain is a part of the main website.

Does subdomain affect main domain SEO?

While subdomains are often thought of as separate entities from the main website, they can positively impact the ranking of the main domain . Furthermore, due to additional keywords, they can also rank for terms for which the main domain doesn’t rank highly.

Reference articles

>> What is SEO ? Overview of knowledge about SEO website needs to know

>> What is Onpage SEO ? 21 new and best Onpage SEO standards

>> What is Offpage SEO ? Why should you build an Offpage SEO strategy?


Above is an overview of what subdomains are that SEOs need to know. Hope this article will provide you with a lot of useful information. In particular, you can know how to use the right subdomain to maximize its use.

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