DNS (Domain Name System)
DNS is a system that converts domain names (yandex.ru) into IP addresses (77.88.55.77) and back.
What is DNS in simple words
DNS (Domain Name System) is a distributed database that converts domain names (for example, yandex.ru) into IP addresses (for example, 77.88.55.77) and back. Without DNS, you would have to memorize the numeric addresses of each website.
Imagine that DNS is the phone book of the internet. When you type a friend's name in your phone, the phone automatically finds their number. In the same way, DNS finds the IP address of a site by its name.
How DNS works
The name resolution process includes several stages:
- Browser cache: The browser checks its local cache. If the name was resolved earlier, the result is taken from there.
- OS cache: If there is no entry in the browser, the request goes to the operating system.
- Recursive resolver: If there is no entry there either, the request is sent to the provider's DNS server.
- Root server: The resolver contacts one of the 13 root servers.
- TLD server: The root server directs to the top-level domain server (.ru, .com).
- Authoritative server: The TLD server directs to the authoritative DNS server of the domain.
Types of DNS records
- A: Binds a name to an IPv4 address.
- AAAA: Binds a name to an IPv6 address.
- CNAME: Creates a canonical name (alias).
- MX: Specifies the domain's mail server.
- TXT: Stores text information (SPF, DKIM, verification).
- NS: Specifies the authoritative DNS servers of the domain.
DNS and security
DNS attacks include DNS spoofing (response substitution), DNS tunneling (data transmission through DNS requests) and DDoS attacks on DNS servers. DNS over HTTPS (DoH) and DNS over TLS (DoT) are used for protection.
Frequently asked questions
What is DNS in simple words?
DNS is the "phone book of the internet". It converts human-readable names of sites (for example, yandex.ru) into numeric IP addresses that computers understand.
How to check domain DNS records?
Use the nslookup domain.ru or dig domain.ru command in the terminal. Online services: dnschecker.org, mxtoolbox.com.
What is DNS over HTTPS?
DoH (DNS over HTTPS) is a protocol that encrypts DNS requests via HTTPS, protecting them from interception and substitution. It is enabled in the browser or at the OS level.
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