What does the first-level, second-level and third-level domain names mean?

What is a first-level domain name?

The first-level domain name is the top-level domain name. Many friends think that shangdaotong.com is the top-level domain name and www.shangdaotong.com is the first-level domain name. In fact, this is a wrong understanding. shangdaotong.com is the top-level domain name. , which is also a first-level domain name.

What is a second-level domain name? What is a third-level domain name?

Theoretically, a top-level domain name can have countless sub-domain names, and it can have countless second-level, third-level or even higher-level sub-domain names.

The first subdomain name assigned under the top-level domain name is called the second-level domain name of the domain name, such as seo.shangdaotong.com; similarly, the second-level domain name assigned in the second-level domain name Another domain name, such as ceshi.seo.shangdaotong.com, is called a third-level domain name, and so on.

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