What is the difference between a first-level domain name and a two-level domain name? What are the roles of each?

The difference between a level two domain name and a first-level domain name:

Level two domain name is dependent on the existence of a domain name exists, that is, the top-level domain name disappears, two-level domain name will no longer exist, instead, the two-level domain name site does not, the main domain is not affected.

Role:

1. First-level domain name is also called top-level domain name, we need to note that www.lisp.com this form of domain name is not a domain name, it is only a two-level domain name, that is, www is just a host name

The real first-level domain name is composed of a legitimate string + domain name suffix, so, lisp.com this form of domain name is a domain name, Lisp is the domain name,. com is the domain name suffix, can be. NET is also a domain name suffix

2. The so-called two-level domain name is actually a first-level domain name under the hostname, as the name implies, it is in front of a first-class domain name plus a string, such as asdx.lisp.com, it can have the same function as the root top-level domain name, and by setting, can have and with the top-level domain exactly the same function

1. Level two domain name is the domain name of the primary domain.

2. Level two domain name is the domain name that is hosted under the primary domain name, the weight is lower than the primary domain name.

3. Level two domain name belongs to a separate branch, he has his own collection, snapshot, PR value, anti-chain and so on.

4. When the primary domain is punished, the level two domain name will also be punished.

What is the difference between a first-level domain name and a two-level domain name? What are the roles of each?