3.11. Domain paid for, but not working

The article is relevant for the following situations:

  • Registered new domain, but the site is down.
  • Extended existing domain, but the site is not working.
  • The site operates at example.com, and by www.example.com does not open (or vice versa).
  • After making changes to the DNS records of the domain, the site does not work or opens at the old address.
  • The NSs have been changed, but the domain works with the old NSs.

In the DNS system, there is a situation when a server caches data and the state of a domain for a certain period, which is specified using TTL (time-to-live) or configured within the server itself, after which the information is updated. In most cases, the caching period does not exceed 24 hours. Such caching can be encountered when changing DNS records of a domain, NS, as well as after registering or restoring a domain.

The following describes 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:

  1. Your device sends a query to the ISP’s DNS server.
  2. The ISP’s DNS server sends a request to the domain zone’s DNS server (in this case, the .COM zone’s DNS server).
  3. The DNS server of the domain zone responds to the ISP’s DNS server that the domain does not exist.
  4. The ISP’s DNS server tells your device that the domain does not exist.
  5. The ISP’s DNS server stores this information for future use (the storage period for this information can be several hours).

Some time passes and you register domain on our website. We send you a notification that the domain has been successfully registered. You enter a domain address on your device, but still receive a response that such a domain was not found. This is due to the fact that operations now occur that are different from those that occurred in the beginning, namely:

  1. Your device sends a query to the ISP’s DNS server.
  2. The ISP’s DNS server tells your device that the domain does not exist.
    Note: This time the ISP’s DNS server does not send a request to the DNS server of the .COM zone, which already knows about the existence of the domain example.com. This is due to the fact that the ISP’s DNS server remembers that there is no such domain, and it will remember this from 1 to 24 hours.

A similar situation occurs when changing domain records, but, unlike the previous one, the response from the DNS servers of the domain zone (.COM or others) comes indicating the server on which the domain records of the requested domain are located, most often this is the NS hosting provider. In this case, the procedure for obtaining records for the domain example.com something like this:

  1. Your device sends a query to the ISP’s DNS server.
  2. The ISP’s DNS server sends a request to the domain zone’s DNS server (in this case, the .COM zone’s DNS server).
  3. The domain zone DNS server responds to the ISP’s DNS server that the domain data is hosted on the following NS.
  4. The ISP’s DNS server sends a request to the NS reported by the domain zone’s DNS server.
  5. The ISP’s DNS server receives the domain data and transmits it to your device.
  6. The ISP’s DNS server stores this information for future use (the storage period for this information is usually equal to the value of the TTL record).

Next, the ISP’s DNS server either returns data from its cache or performs all requests again. It is impossible to clear the cache of ISP DNS servers, so you need to either wait for the information to be updated on them, or use public DNS.

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