What is a second-level domain name?-php Tutorial

What is a second-level domain name? I heard that when I applied for a domain name, I gave two domain names, one with www, the other without www, and the other was a second-level domain name without www, I don't know. Is there a third-level domain name or a fourth-level domain name? why N-level domain name.

Reply to discussion (solution)

If you use a variety of cloud services, the second-level domain name will be provided
Example: abc.sinaapp.com

For example, my domain name is www.abcdefg.com.
Can I define my second-level domain name, or can the service provider confirm it for me?

For example, my domain name is www.abcdefg.com.
Can I define my second-level domain name, or can the service provider confirm it for me?

You can set the category in the domain name management background.

The domain name consists of the root domain, domain name, and host name.
A second-level domain name is a domain name that does not contain a host name applied to the domain name service provider.
That is, the abcdefg.com section of www.abcdefg.com, and the domain name of the host name is resolved by yourself.

The domain name consists of the root domain, domain name, and host name.
A second-level domain name is a domain name that does not contain a host name applied to the domain name service provider.
That is, the abcdefg.com section of www.abcdefg.com, and the domain name of the host name is resolved by yourself.

If I want to resolve another second-level domain name, for example, cade.abcdefg.com, does it mean that cade is a server name?

Yes
As long as your domain name supports second-level domain names (you can confirm this with the service provider)

Yes
As long as your domain name supports second-level domain names (you can confirm this with the service provider)

Do I have to pay extra money to the domain name provider? for this second-level domain name

I don't know. you should ask the service provider

Yes
As long as your domain name supports second-level domain names (you can confirm this with the service provider)

Do I have to pay extra money to the domain name provider? for this second-level domain name

So far, I have not seen any extra payments. You have registered a domain name. you can use its subdomain name as needed.

As long as you have a domain name, second-level domain name resolution can be used,

For example, Level 1 domain name http://www.abc.com, level 2 domain name is defined under the level 1 domain name of a sub domain name, such as: http://123.abc.com or http://xyz.abc.com, are level 2 domain name, level 2 domain name based on level 1 domain name for resolution, third-level domain name based on second-level domain name resolution, such as setting a successful http://xyz.abc.com, and then set the http://abcdefg.xyz.abc.com under it, it becomes a third-level domain name, N-level domain name layer settings, the same reason can be obtained.

Didn't the second-level domain name be set directly in the configuration file of the server program?

For example, Level 1 domain name http://www.abc.com, level 2 domain name is defined under the level 1 domain name of a sub domain name, such as: http://123.abc.com or http://xyz.abc.com, are level 2 domain name, level 2 domain name based on level 1 domain name for resolution, third-level domain name based on second-level domain name resolution, such as setting a successful http://xyz.abc.com, and then set the http://abcdefg.xyz.abc.com under it, it becomes a third-level domain name, N-level domain name layer settings, the same reason can be obtained.

If it is defined by yourself, it seems that the second-level or above domain names do not have to pay for them to use?

To put it simply, you have to deal with three Merchants: The Registrar, the domain name resolution provider, and the space (server) supplier.
The registrar only registers a domain name such as xxx.com. during registration, you are allowed to specify a dns (domain name resolution provider), which can be changed. The charges vary slightly.
The domain name resolution provider can help you resolve xxx.com to an ip address (server). It can also resolve the prefix xxx.xxx.com to the corresponding ip address. whether it is charged depends on the service. Generally, the www prefix is provided for free, that is, www.xxx.com.
The space supplier is the owner of the ip address mentioned above. it can store and open the ip address to you as a web (http) service. The fee depends on the service protocol.

Your current situation is that two or three of the above three sellers are the same, and the merger charges may occur.

So when you register, the most important thing is to find a trusted domain name registrar, you have the permission to change the dns, otherwise your domain name resolution right will be controlled by others, when there is a dispute, he will not be able to find your website (no matter what space you change, you cannot specify the dns is just a white-box), this is a lot of things I see. Of course, if the legal documents record that you are the domain name owner, you can appeal to the domain name Management Center to retrieve control rights, but these are paperwork requests and procedures are quite troublesome.

If you want to pay for a domain name with a prefix, there are two methods:
1. you must assume the role of a domain name resolution provider. of course, you must have related DNS servers or similar software. if there are not many sub-domain names, you do not have to use server hardware, however, the response capability of bandwidth and concurrency must be satisfied.
2. now there are some free domain name resolution providers. you can find them by yourself. I will not talk about it here because of the wall problems.

Generally, merchants will not be too black. it is enough to find a trusted company and set its own dns. a certain number of name records can be added.

The brother mentioned above makes it clear:

Www.baidu.com Level 1, but in general, you can simply enter baidu.com in the browser, that is, www can be saved.
Wenku.baidu.com is Level 2 and cannot be omitted. www cannot be added at the beginning.
Level 3 is similar. the domain name is added to the leftmost side, with a dot "." followed by Level 2.
Level 4 can be referred to level 3.

A little messy

No answer to the charge questions yet

No answer to the charge questions yet

Didn't you see it? I made it very clear.

No answer to the charge questions yet

Didn't you see it? I made it very clear.

I mean second-level domain name or third-level domain name charges

No answer to the charge questions yet

Didn't you see it? I made it very clear.

I mean second-level domain name or third-level domain name charges

I said it depends on the service. there is no such charge in the world, but it only depends on whether the DNS service provider provides the service. that is to say, different types of services are possible from free to daily prices.
Theoretically ~ It should be free of charge, but this also occupies server resources, so service providers may also limit the ability of large businesses to add unlimited
If your registrar does not provide a multi-level domain name, but you can modify the specified DNS, you can designate another free or paid DNS service provider