How DNS and Whois Work

Clients often ask us why it can take so long (up to 72 hours) for domain name servers to change. We'll try to explain this in more detail.

Let's start with the fact that every server has two addresses. One is the domain name, which is easy to remember, such as nic.ua. The second is the Internet Protocol (IP) address, a unique sequence of numbers, such as 192.0.2.0.

DNS (domain name system) is the internet's addressing system that maps domains to IP addresses. It is a database that stores all domain names and their corresponding IP addresses. Name servers (NS) are the servers that store the DNS database records.

How DNS works:

1. After you type domain.org into your browser, your computer sends a request to your ISP's DNS server to get the IP address where the domain is located.
2. If the provider's DNS servers don't find this information in their cache, they send a request to the root DNS server to find the name servers associated with this domain. In our example, this is the .ORG domain.
3. The .ORG domain's DNS server searches for information about the hosting provider's name servers where the domain.org website is located and reports the IP address found to the provider's caching DNS server.
4. The internet service provider's DNS server then transmits the IP address to your browser, which then loads the website. The IP address is then added to the provider's cache to reduce the load on internet connections and speed up future information retrieval.

If you change your domain's NS, the changes themselves occur instantly. However, your provider's information may take some time to update, and this time varies for each DNS server (from 1 minute to 72 hours). Furthermore, if someone using your internet service provider visited your website before you changed the IP address or nameservers, the old information will remain in the caching DNS server's database until the cache is updated. However, with other providers, your website may open from the new IP address.

To find out if the NS has changed, you can access the public Whois database. For example, on the websitedig.ua.

The main purpose of Whois is to find out the registration data of IP addresses, domains, etc. A domain record is issued in text form and typically contains the name and contact information of the domain owner, registrar information, DNS server names, registration date, and expiration date of the domain.

Whois is often used to check whether a domain is available for registration.

If you have any further questions about DNS and Whois, please ask them in the comments. We'll do our best to answer them :)

The images are taken from the official ICANN website and translated by us.