Is this domain a second-level domain name?

bbs.example.com

I referred to the domain name knowledge on Wikipedia, and have read through the page, but I still don't know what is a second-level domain name? The page says com is a TLD (Top Level Domain), and the TLDs are the highest level of domain names on the Internet.

It says. bbs.example.com is a third-level domain name? But someone told me bbs.example.com is a second-level domain name. .com is the TLD, not the domain name.

Which is ri开发者_C百科ght? Thank you.

My answer is maybe too late, but I wanted to add some details to @icktoofay's correct answer.

The Domain Name System is a hierarchical naming system (tree). The hierarchy is represented by each part separated by a dot, that are interpreted from right to left for example: bbs.example.com. should be interpreted as .com.example.bbs and decomposed as:

• Layer 1: .com is a Top Level Domain
• Layer 2:.com.example is a Second Level Domain
• Layer 3:.com.example.bbs is a Third Level Domain

That's where the notion of top, second and third level are coming from.

I wrote an article on my personal blog introducing the domain name system if you are interested where I describe this in more detail: What's a domain name and what's behind the scene

bbs in bbs.example.com is a third-level domain name. example in example.com is a second-level domain name. com is a top-level domain name. (TLD)

Use the separate list of tlds from https://publicsuffix.org/list/public_suffix_list.dat

This is maintained by mozilla.

By using this list of tld you can find the domain level.

Let me know if you have any more queries.