What is a Domain Name? What is a domain name server?

Register your domain name and purchase hosting services, you need to buy the domain name resolves to the host, to see the site content. In most cases, change the DNS domain name server, and can not immediately see the site's content, but in a few hours, or even a day or two to open your site.

To understand why the domain name resolution so long, we need to understand the process of domain name resolution and DNS server role.

Each computer on the Internet is assigned a IP address, data transfer is actually carried out between different IP addresses. Including our use of computers at home, connect to the Internet in the future have also been assigned a IP address, the IP address most of the cases, is dynamic. This means that you turn off the modem, re-open Internet, your Internet access were randomly assigned to a new Chamber of Commerce IP address.

Web server is essentially a computer station with Internet access, but configuration is more suitable as a server, and on the data center, maintaining low temperature, low dust environment, but there are safety measures. These servers use a fixed IP address connected to the Internet.

A domain name resolution to a server, and the page files on this server, the user's computer know to which server to obtain the domain name web page information. This is achieved through domain name server.

Domain name server is the English acronym for Domain Name Server. Each domain name must have at least two DNS servers, so if one DNS server problem, the other can return the data on this domain. DNS server can have more than two, but all of these DNS servers DNS records should be the same.

In the DNS server to keep a record of the DNS domain name, such as A records, MX records. A record is used to specify the host name (or domain) the corresponding IP address. MX records to resolve mail server name. In many cases.

When a viewer in the browser address box into one name, or click on a link from another site to this domain name, browser access to the user's Internet domain name to issue the request, access providers DNS server to query domain name database, see the domain name DNS server is. Crawl and then to DNS records DNS server, which is to obtain the domain name point to which IP address. Access to the IP information, go to the access provider's server IP address corresponding to the server to crawl content, and then transmitted to the requesting browser.

This process is described it's quite complex, but in fact less than a second or two to complete.

Domain name resolution takes a long time the reason is because Internet access providers, such as Beijing Telecom and Henan telecommunications, in order to speed up the pace of the user opens the page, usually in their DNS servers cache the DNS records of many domain name. That the access provider's customers to open a Web page, the access provider's domain name servers need to query the database, but to their own cache of DNS records to be used directly to speed up user access to the site. This is the advantage.

Drawback is that Internet access providers ISP's cache is stored for some time, only when it is updated as needed, but there is no standard frequency of updates. Some ISP may be updated 1 hour, some may take up to 12 days before updated.

So the new domain name registration in general analytical Fandao faster. Because all of the ISP are not cached, the user access to query when the ISP is the domain database, get the latest DNS data.

The old domain name if you change the DNS records, but the rest of the world's ISP cache data is not immediately updated. So different users under different ISP, and some can be relatively fast access to the new DNS records, and some have to wait for the next update ISP cache.

Finally, a note of the point is, DNS server and Web server may be the same provider, can also be different. Web hosting providers usually also provide their own DNS server, so the user only to point their domain name web hosting provider's own domain name server on it. Some users like to use the domain name registration service provider DNS server, this time the user must in the DNS server, domain name registration business to change DNS records, such as A, MX records until the IP address of the virtual hosting providers.

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