computer networking (at layer 3 of the OSP model) is done with IP addresses but for as humans it's hard to remember IP addresses, it's much easier to remember names. This why we need something such as DNS to convert any domain name we type into an IP address. You can think on DNS as a huge phonebook or database where each corresponding name has an IP.
A server which is responsible for resolving DNS queries.
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<summary>What is the resolution sequence of: www.site.com</summary><br><b>
It's resolved in this order:
1) .
2) .com
3) site.com
4) www.site.com
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<summary>What is a domain name registrar?</summary><br><b>
[Cloudflare](https://www.cloudflare.com/en-gb/learning/dns/glossary/what-is-a-domain-name-registrar): "A domain name registrar provides domain name registrations to the general public. A common misconception is that registrars sell domain names; these domain names are actually owned by registries and can only be leased by users."
* The Resolver is a server, usually configured by your ISP when you connect to the internet, that responsible for resolving your query by contacting other DNS servers
* The Resolver contacts the root nameserver (aka as .)
* The root nameserver either responds with the address you are looking for or it responds with the address of the relevant Top Level Domain DNS server (if your address ends with org then the org TLD)
* The Resolver then contacts the TLD DNS. TLD DNS might respond with the address you are looking for. If it doesn't has the information, it will provide the address of SLD DNS server
* SLD DNS server will reply with the address to the resolver
* The Resolver passes this information to the browser while your OS also stores this information in the cache
* The user cab browse the website with happiness and joy :D
[varonis.com](https://www.varonis.com/blog/dns-ttl): "DNS TTL (time to live) is a setting that tells the DNS resolver how long to cache a query before requesting a new one. The information gathered is then stored in the cache of the recursive or local resolver for the TTL before it reaches back out to collect new, updated details."
<summary>What types of zones are there?</summary><br><b>
There are several types, including:
* Primary zone: A primary zone is a read/write zone that is stored in a master DNS server.
* Secondary zone: A secondary zone is a read-only copy of a primary zone that is stored in a slave DNS server.
* Stub zone: A stub zone is a type of zone that contains only the essential information about a domain name. It is used to reduce the amount of DNS traffic and improve the efficiency of the DNS resolution process.
