What is a record? What is an alias record (cname )? What is an MX record? What is an NS record?

A (Address) Record

Is used to specify the IP address record corresponding to the Host Name (or domain name. You can direct the website server under this domain name to your web server. You can also set a second-level domain name for your domain name.

  

Alias record (cname)

It is also called a canonical name. This record allows you to map multiple names to the same computer. It is usually used on computers that provide both WWW and mail services. For example, there is a computer named "host.mydomain.com" (a record ). It provides WWW and mail services at the same time, in order to facilitate user access to the service. You can set two aliases (cname) for the computer: WWW and mail. The full names of these two aliases are www.mydomain.com and mail.mydomain.com ". In fact, they all point to "host.mydomain.com ". The same method can be used when you have multiple domain names that need to point to the same server IP address, in this case, you can direct a domain name as a record to the server IP address and then alias other domain names to the domain name previously recorded as a record, when the IP address of your server changes, you do not need to bother to point to the domain name that only needs to change the record, and the domain name that makes the alias will also be changed automatically. to the new IP address.

 

Mx (Mail exchanger) Record

A mail exchange Record pointing to an email server. It is used to locate the email server based on the recipient's address suffix when the email system sends an email. For example, when a user on the Internet wants to send a letter to a user@mydomain.com, the user's email system looks for the MX record for the domain name mydomain.com through DNS, if the MX record exists, the user's computer sends the email to the email server specified by the MX record.

Methods for checking the existence of MX records
A very useful tool for DNS query is NSlookup, which can be used to query various data in DNS. You can directly run NSLookup in Windows command line to enter an interactive mode, where you can query various types of DNS data.
DNS name resolution data can be of different types, including the SOA type data with the parameter set for this zone, and the type data with the IP address corresponding to the parameter set for this zone, there is MX data set for mail exchange. These different types of data can be queried through the NSLookup interactive mode. During the Query Process, you can use the set type command to set the corresponding Query type.
For example:
C: \> NSLookup
Default Server: [202.106.184.166]
Address: 202.106.184.166

> Set type = mx
> Sina.com.cn
Default Server: [202.106.184.166]
Address: 202.106.184.166

Non-Authoritative Answer:
Sina.com.cn MX preference = 10, mail exchanger = sinamx.sina.com.cn

Sina.com.cn nameserver = ns1.sina.com.cn
Sina.com.cn nameserver = ns3.sina.com.cn
Sinamx.sina.com.cn Internet address = 202.106.187.179
Sinamx.sina.com.cn Internet address = 202.106.182.230
Ns1.sina.com.cn Internet address = 202.106.184.166
Ns3.sina.com.cn Internet address = 202.108.44.55

Simple tips:You can also use commands such as NSLookup-Qt = mx zzy.cn to query the MX records of zzy.cn.

Appendix: China Resources enterprise Post Office MX record practices
Single-line enterprise Post Office (Telecom single line): mx1.cnm.cn.
Two-line enterprise Post Office (China Telecom + China Netcom also has lines): mx2.cnm.cn.

 

NS (Name Server) Record

Is a Domain Name Server record, used to specify the DNS server for the domain name to be resolved.

 

If the MX record of a domain name does not exist, a message similar to the following appears:
C: \> NSLookup
> Set type = mx
> Amafdsfxit.com.cn
Default Server: [202.106.184.166]
Address: 202.106.184.166

* ** 202.106.184.166 can't find amaxit.com.cn: non-existent domain