The article is relevant for the following situations:
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I registered new domain, but the site is down.
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I extended domain, but the site did not work.
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The site operates at
example.comand bywww.example.comdoes not open (or vice versa). -
After making changes to DNS-records of the domain the site does not work or opens at the old address.
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NS servers have been changed, but the domain still works on old NS.
Short description
In system DNS there is a situation when a server caches data and the state of the domain for a certain period, specified by the TTL (time-to-live) or within the server itself, after which the information is updated. The maximum cache time can be up to 72 hours. Such caching can be encountered when NS servers, A (Ip to which the domain is directed) or other records have been changed, as well as after registering or restoring a domain.
Detailed description
How the Internet Domain Name System works:
Before registering a domain name, you enter the domain name example.com on your device. The following operations take place:
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Your device is sending a request to DNS-server of the internet provider.
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DNS-the ISP server sends a request to DNS-server of the domain zone (in this case it is DNS COM server).
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DNS-the domain zone server responds DNS-server of the ISP that the domain does not exist.
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DNS-The server of the ISP replies to your device that the domain does not exist.
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DNS- the server stores this information on its own, in case of further use (the period of storing this information is quite long and can take several hours).
Some time passes and you fill out an application on our website for domain name registration... We send you a notification that the domain has been registered. You enter the domain address on your device, but you still get the answer that no such domain was found. This is due to the fact that now there are operations that differ from those that happened at the beginning, namely:
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Your device is sending a request to DNS-server of the internet provider.
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DNS-The server of the ISP replies to your device that the domain does not exist.
Note: DNS-the server of the ISP now does not send a request DNS-server .COM, which already knows about the existence of the domainexample.com... This is due to the fact that DNS-the ISP's server remembered that there is no such domain, and it will remember it from 1 to 24 hours.
A similar situation occurs when changing domain records, but unlike the previous one - the answer from DNS-servers of the domain zone (.COM or others) comes with an indication of the server that hosts the domain records of the requested address, most often it is the provider's NS server. In this case, the procedure for obtaining records for the domain example.com roughly as follows:
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Your device is sending a request to DNS-server of the internet provider.
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DNS-the ISP server sends a request to DNS-server of the domain zone (in this case it is DNS COM server).
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DNS-the domain zone server responds DNS- to the server of the Internet provider that the domain data is located on the following NS.
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DNS-the server of the Internet provider makes a request to the NS servers that it pointed to DNS domain zone server.
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DNS-the server of the Internet provider receives the domain data and transmits it to your device.
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DNS-the server of the Internet provider stores this information for further use (the period of storing this information is usually equal to the value of the TTL record).
Subsequent retrieval of information is done either by providing a cached response, or by making all requests anew. But clear the cache DNS-servers of Internet providers is simply impossible, you just have to wait for their independent update.
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