Domain name management knowledge, such as a record, MX record, cname record, and NS record

Source: Internet
Author: User
Tags website server domain name server mail exchange mx record nameserver nslookup nslookup command url forwarding

Domain name management knowledge, such as a record, MX record, cname record, and NS record
Write by admin /? P = 98
What is domain name resolution?
Domain name resolution is the process of converting the domain name to the IP address. An IP address is a digital address that identifies you on the Internet. To make it easy to remember, use a domain name instead of an IP address to identify the site address. Domain name resolution is completed by the DNS server.
1. A record: IP point of the Web Server
The A (Address) record is used to specify the IP address record corresponding to the Host Name (or domain name.
Note: 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 own domain name.
That is to say: through a record, you can set different domain names to be transferred to different IP addresses! For example:
Go to to IP address 321.32.321.321 to IP to IP
There are three more records related to:
Domain name a record: A (Address) record is the record corresponding to the domain name and IP address.
Domain Name alias record: the canonical name (cname, canonical name) record is the record corresponding to the domain name and the domain name alias.
Dynamic domain name resolution: the IP address corresponding to the domain name in the record is a static IP address. Resolve the domain name to a dynamic IP address, which is called dynamic domain name resolution.
Generally, Domain Name Service Providers only provide a record for free, and do not provide dynamic domain name resolution for free.
2. MX record (mail exchange): mail route record
Note: You can direct the email server under this domain name to your own mail server, and then you can control all mailbox settings on your own.
You only need to enter the host name or IP address of your server online to transfer all emails under your domain name to your own email server.
It is to separate the email server in your domain name and set it to another IP address!
For example, If you set a record to point to, and MX record to point to,
When your DNS server receives a mail route request from someone else, it will interpret the request to! When others access your webpage, they still access
3. cname (canonical name) Record (alias from one domain name to another)
You can transfer all registered domain names to one primary domain name! Different from the record, the cname alias record can be a description of a domain name, not necessarily an IP address!
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 "" (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 ".
In fact, they all point to " ".
4. URL (Uniform Resource Locator) forwarding: URL forwarding
Function: if you do not have an independent server (that is, you do not have an independent IP address) or you still have a domain name B, you want to access the content of domain name B when accessing domain name, in this case, you can use URL transfer.
URL forwarding can be forwarded to a directory or even a file. However, cname is not acceptable, which is the main difference between URL forwarding and cname.
5. The NS (Name Server) record is a Domain Name Server record used to specify the DNS server to which the domain name is resolved.
6. What is the TTL value?
The full name of TTL value is "time to live". Simply put, it indicates the cache time of DNS records on the DNS server. To understand the TTL value, take a look at the following example:
Assume that the IP address of the domain name (in fact, this is a DNS record, which usually indicates that there is a host named myhost in the domain) is, the TTL is 10 minutes.
This domain name or record is stored on a DNS server named
Now there is a user typing the address (also known as URL): what will happen to the at this time?
The DNS server specified by the visitor (or its ISP, Internet service provider, which is dynamically allocated to him) tries to explain to the visitor,
Of course, because the DNS server does not contain the message "", it cannot be resolved immediately. However, after recursive query by global DNS,
Finally, the DNS server is located, and the DNS server sends the IP address corresponding to to the DNS server,
Then, tells the user the result. in order to accelerate the resolution of the record in the future, the result will be retained for a period of time,
This is the TTL time. If you have another resolution request for the record within this period, it will directly tell the user When the TTL expires, it will repeat the above process.
View the usage of the NSLookup command for querying domain name a records, MX records, cname records, and NS records
You can use ping to view the IP address of a domain name. Only the record of the domain name can be found. You can use the NSLookup command to query the MX record, cname record, or NS record of the domain name. NSLookup is a built-in command for Windows NT/2000/XP, UNIX, Linux, and other systems. (Not in Windows 98/ME ).
In the Windows doscommand line window or Unix/Linux Command Line, enter NSLookup
C:/> NSLookup
Default Server:
"Default Server" and "Address" are the domain names and addresses of the DNS servers currently used for Internet access.
At this time, enter the domain name directly at the prompt, and you can find the record of the domain name. For example:
Non-Authoritative Answer
"Non-Authoritative Answer" indicates that the query result is returned from the DNS cache.
Enter set querytype = Mx, and then enter the domain name to query MX records. For example:
> Set querytype = NS
Non-Authoritative Answer: nameserver = nameserver =
> Set querytype = mx
Non-Authoritative Answer: MX preference = 10, mail exchang m nameserver = nameserver =
Enter set querytype = cname, and then enter the domain name to query the cname record.
Enter set querytype = NS, and then enter the domain name to query NS records.
From- /? P = 98

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