1. DNS
DNS, Domain Name System or Domain Name Service. The Domain Name System assigns domain name addresses and IP addresses to hosts on the Internet. Since all computers in the network must have an IP address to identify and communicate with each other, it is obviously impossible for us to remember a large series of IP addresses to access the website, so users use domain name addresses, and the DNS system The function is to automatically translate the domain name address into an IP address. Domain Name Service is an Internet tool that runs the Domain Name System. The server that performs the domain name service is called the DNS server, and the query of the domain name service is answered by the DNS server.
- DNS is a domain name server, and its task is to determine the resolution of domain names, such as A records, MX records, and so on.
Any domain name has at least one DNS, usually two. But why more than 2? Because DNS can be processed in a round-robin fashion, the first one that fails to resolve can find the second one. In this way, as long as one DNS resolution is normal, the normal use of the domain name will not be affected.
Determine the DNS of the domain name, go to http://www.internic.net/whois.html and enter the domain name you want to query to see it. This is the International Domain Name Management Center. sole authority. As long as a domain name can be found here, it means that the domain name is valid. It says when you are due, when is due.
Valid DNS indicates who is currently working on the DNS server. For example, if the query result is NS.XINNETDNS.COM, NS.XINNET.CN (New Network Xinhai), it means that the current domain name is NS.XINNETDNS.COM, NS.XINNET .CN (New Net Xinhai) is responsible for the analysis. Other DNS settings that are not displayed are invalid.
DNS can be modified. After modification, it will take 24-72 hours before all DNS servers around the world can be refreshed. Internic information is generally available after 24 hours. In addition, the modification process does not mean that the domain name will stop parsing, as long as you have done the parsing on both sides. If it takes effect, the new DNS is working. If it doesn't work. It's the old DNS at work. Either it works or it doesn't. There is no time when neither will work. Therefore, domain name resolution will not be interrupted. The premise is that both sides have been analyzed
2. A record
A (Address) record is used to specify the IP address record corresponding to the host name (or domain name). Users can point the website server under the domain name to their own web server. You can also set up subdomains of your domain name. Generally speaking, the A record is the IP of the server, and the domain name binding A record is to tell the DNS, when you enter the domain name, it will guide you to the server corresponding to the A record set in the DNS.
3. Subdomains
The subdomain name is the same as the second-level domain name, but it is more extended than the second-level domain name. For example, if we continue to expand the host name of the domain name and set the host name to bbs.at, then a third-level domain name can be established: bbs.at.abc.com , of course, you can also establish a fourth-level domain name bbs.at.go.abc.com, a fifth-level domain name bbs.at.go.home.abc.com, and so on, you can create unlimited levels of domain names, we collectively call these domain names as A subdomain of the top-level domain abc.com.
Fourth, the CNAME alias points to the record
CNAME (Canonical Name) records, usually referred to as aliases. Here, you can define a host alias, such as setting ftp.google.com to point to a host www.google.com, then you can use ftp.google.com to visit www.google.com in the future.
5. MX records
MX records are also called mail routing records. Users can point the mail server under the domain name to their own mail server, and then they can control all mailbox settings by themselves. You only need to fill in the IP address of your server online, and all the mails under your domain name can be transferred to the corresponding mail server you set by yourself. Simply put, by manipulating the MX records, you can get the post office that ends with your domain name.
6. TXT record
TXT record, generally refers to the description set for a certain host name or domain name, such as: admin IN TXT "administrator, phone: 13901234569" mail IN TXT "mail host, stored in xxx, administrator: AAA" Jim IN TXT "contact : [email protected]" That is, you can set TXT so that others can contact you.
7. SRV record
SRV record: Typically used when setting up for Microsoft's Active Directory. DNS can be independent of Active Directory, but Active Directory must have the help of DNS to work. For Active Directory to work properly, the DNS server must support Service Location (SRV) resource records, which map service names to the names of the servers that provide the service. Active Directory clients and domain controllers use SRV resource records to determine the IP address of the domain controller. Please refer to the corresponding website for this technical detail.
Eight, TTL value
The full name of the TTL value is "Time To Live", which simply means that the DNS record is cached on the DNS server. To understand the TTL value, please look at the following example: Suppose, there is such a domain name myhost.abc.com (in fact, this is a DNS record, usually indicating that there is a host named myhost in the abc.com domain) corresponding to The IP address is 1.1.1.1 and it has a TTL of 10 minutes. This domain name or record is stored on a DNS server called dns.abc.com. Now a user types an address (aka URL) into a browser: http://myhost.abc.com What happens? The DNS server specified by the visitor (or his ISP, Internet service provider, dynamically assigned to him) 8.8.8.8 will try to explain myhost.abc.com for him. Of course, the DNS server 8.8.8.8 does not contain The information myhost.abc.com cannot be resolved immediately, but after a recursive global DNS query, the DNS server dns.abc.com is finally located, and the DNS server dns.abc.com will be myhost.abc.com. The IP address 1.1.1.1 corresponding to com tells 8.8.8.8 this DNS server, and then 8.8.8.8 tells the user the result. 8.8.8.8 In order to speed up the analysis of the record of myhost.abc.com in the future, the result of 1.1.1.1 will be kept for a period of time, which is the TTL time. For the parsing request of this record, it directly tells the user 1.1.1.1, and when the TTL expires, the above process will be repeated.
9. Pan domain name and pan resolution
Generic domain name refers to all unestablished subdomains under a domain name root in the form of *.Domain.com. Pan resolution is to resolve the A record of *.Domain.com to a certain IP address, and then others can access the site you resolve by accessing any prefix .domain.com.
For example: the domain name root name.com only has two domain name records, www.name.com and name.com, then the domain name records such as ftp.name.com mail.name.com bbs.name.com do not exist, but After establishing the generic domain name record *.name.com for the domain name root name.com, *.name.com covers all non-existing subdomain records such as ftp.name.com mail.name.com bbs.name.com. You can define *.name.com to point to an IP, then when a visitor enters ftp.name.com mail.name.com or bbs.name.com, the visitor will directly access your defined *.name. com's IP.
10. Domain name binding
What is domain name binding? Domain name binding means that domain name binding refers to the spatial binding of a domain name and a host (that is, a server). In a specific space, when a visitor accesses your domain name, they will open the web page you stored in the space. In short, it is the process of resolving the domain name to the server IP, and then setting the domain name on the server to have permission to access.
11. Domain name transfer
Domain forwarding is also known as domain name (URL) pointing or domain name forwarding. When the user enters your domain name in the address bar, it will automatically jump to another network address (URL) you specify. Assuming abc.com is your registered domain name, the URL forwarding service can be used to automatically redirect to another URL when a user visits http://www.abc.com, such as: My space does not support the function of binding to a directory , So for the convenience of visitors, I set up: http://bbs.bnnb.net to visit, this is achieved by setting up the URL forwarding service to forward to http: //www.bnnb.net/bbs, so that You can easily realize that multiple domain names point to a website or website sub-directory; in addition, through the URL forwarding service, you can easily realize the automatic forwarding of your Chinese domain name to your English domain name main site. Another advantage of domain forwarding is that it can compress long domain names and replace them with short domain names, so that your visitors do not need to enter such long domain names.