What is the relationship between the main domain name and the subdomain name? What is the difference?
DomainCn
In the digital world of the Internet, domain names are the entrances for users to access websites, just like house numbers in the real world. As the core components of the domain name system, primary domain names and subdomain names have both close hierarchical associations and independent functional characteristics. Understanding the relationship and difference between the two can not only help us better manage the website architecture, but also optimize the allocation and utilization of network resources.
1. What is the relationship between primary domain names and subdomain names?
The primary domain name and subdomain name are in a hierarchical relationship of "trunk and branches", forming an organic whole through DNS (Domain Name System).
1. Hierarchical dependency
Subdomain names are branches of the primary domain name, which are formed by adding a prefix (such as `mail.` or `blog.`) to the primary domain name. For example, the subdomain name of `example.com` is `mail.example.com`. This structure is similar to the headquarters and branches in the corporate organizational structure. Subdomain names must be attached to the primary domain name and cannot exist independently of the primary domain name.
2. Management authority inheritance
The holder of the primary domain name has absolute control over the subdomain name. For example, users can create, delete or modify the resolution record of a subdomain through the DNS management interface of the main domain name to determine the server IP or service type it points to.
3. Resource sharing and collaboration
Subdomains can share the SSL certificate, server resources or security policies of the main domain name to reduce operation and maintenance costs. For example, the SSL certificate of the main domain name `baidu.com` can automatically cover subdomains such as `news.baidu.com` to ensure HTTPS encryption for the entire site.
2. What is the difference between the main domain name and the subdomain name?
Despite the association, the main domain name and the subdomain name have significant differences in function, authority and application scenarios.
1. Independence and authority
Main domain name: It is the core identifier of the website, with uniqueness and highest authority. For example, `taobao.com` represents the official website of Taobao, and its SEO weight and search engine inclusion priority are usually higher than subdomain names.
Subdomain name: It is attached to the main domain name and has lower authority. For example, `login.taobao.com` is only used as a login entrance, and its content may not be regarded as an independent site by search engines.
2. Management authority and flexibility
Primary domain name: The holder can directly configure the DNS root record (such as A record, MX record) to determine the core service direction of the website.
Subdomain name: More flexible management, can be quickly created or deleted according to business needs.
3. Technical implementation and resource allocation
Primary domain name: Usually points to the core server, carrying the main functions of the website (such as user login, database interaction).
Subdomain name: Can point to an independent server or share the main server resources. For example, `cdn.example.com` may point to a dedicated CDN node to accelerate static resources, while `blog.example.com` may share the same server with the main site.
4. Application scenario differences
Primary domain name: Applicable to brand official website, core business platform (such as `jd.com`).
Subdomain name: Mostly used for functional segmentation, such as test environment or international business.
The relationship between the primary domain name and the subdomain name is essentially a microcosm of the Internet hierarchical architecture. The primary domain name is like the central landmark of the city, carrying the core functions and brand value; the subdomain name is like a characteristic block distributed everywhere, meeting diverse business needs. Understanding the differences and connections between the two can not only improve the efficiency of the website's technical architecture, but also provide strong support for the company's digital strategy.
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