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What is DNS? DNS Terms, Components and Basic Concepts

DNS is the system that translates domain names into IP addresses.
Understanding DNS allows you to quickly resolve website and server problems.

What Will You Learn in This Guide?​

  • Basic logic of DNS
  • Domain name and IP relationship
  • DNS record types
  • How DNS queries work

What is DNS (Domain Name System)?​

DNS translates human-friendly domain names into IP addresses.
Browsers work with IP, people use domain names.

Example:
ornek.com → 185.XX.XX.XX

Basic DNS Terms​

Domain Name​

A domain name is the readable name of an internet resource.
Example: ornek.com

IP Address​

An IP address is a unique ID on the network.
IPv4 example: 192.168.1.10

DNS maps the domain name to this number.

Top Level Domain (TLD)​

It is the rightmost part of the domain name.
Examples: .com, .net, .org, .edu

TLDs are governed by ICANN.

Host​

Host is the specific service under the domain name.
Examples:

  • www.ornek.com
  • api.ornek.com

Subdomain​

Subdomain is the subdivision of the domain name.
Example: panel.ornek.com

Host represents the service.
Subdomain expands the domain.

FQDN (Fully Qualified Domain Name)​

FQDN is the fully qualified domain name.
DNS is defined down to the root.

Example: mail.google.com.

yaml

The trailing dot represents the DNS root.

How Do DNS Servers Work?​

DNS has a hierarchical structure.
Queries are resolved top-down.

Root Servers​

It is the top level of the DNS system.
There are a total of 13 root server groups.

Root servers redirect TLD information.

TLD Servers​

Knows fields such as .com, .org.
Returns the authoritative server of the relevant domain name.

Domain Authorized Servers​

It keeps real IP information.
It gives the final response to the client.

Resolver DNS (Resolver)​

It is the server that makes queries on behalf of the user.
Speeds up queries by using cache.

Example resolver:

  • ISP DNS
  • Google DNS (8.8.8.8)

Zone File​

The Zone file keeps DNS records.
Every domain name has a zone file.

Defines the authority limit.

$ORIGIN​

It is the domain name for which Zone is authorized.
The default is the root point.

TTL (Time To Live)​

It is the time the DNS record remains in the cache.
It is questioned again when the time expires.

Common DNS Record Types​

SOA Record​

It is the starting record of the Zone.
It is mandatory in every zone file.

example.com. IN SOA ns1.example.com. admin.example.com. (
  2025121601
  3h
  30m
  3w
  1h
)
  • This record defines zone authority.

A and AAAA Records​

It binds the domain name to the IP.


www IN A 192.168.1.10
  • This record maps the IPv4 address.

www IN AAAA 2001:db8::1
  • This record maps the IPv6 address.

CNAME Record​

Redirects one domain name to another name.


www IN CNAME server1
  • Creates additional queries, affects performance.

MX Record​

Identifies e-mail servers.


IN MX 10 mail1.example.com.
IN MX 50 mail2.example.com.
  1. Lower number is higher priority.

NS Registration​

  1. Specifies the DNS servers of the domain name.

IN NS ns1.example.com.
IN NS ns2.example.com.
  • At least two NSs are recommended.

PTR Record (Reverse DNS)​

  1. Provides conversion from IP to domain name.

10.1.168.192.in-addr.arpa IN PTR server.example.com.
  • It is critical for mail servers.

CAA Registration​

  1. Limits SSL certificate authority.

example.com IN CAA 0 issue "letsencrypt.org"
  • Prevents unauthorized certificate generation.

Frequently Asked Questions (FAQ)​

1. Why is DNS slow sometimes? TTL and cache time are effective.

2. Why is CNAME not recommended? Creates additional query.

3. Why is PTR registration important? Mail servers check for spam.

4. Is CAA registration required? Recommended for SSL security.

Result​

  • DNS is the invisible backbone of the internet.
  • Correct DNS information means a stable system.

You can safely apply this information in the GenixNode infrastructure.