DNS stands for Domain Name System and functions like a telephone book for the internet: It converts human-readable domain names (e.g., docs.internex.com) into numeric IP addresses (e.g., 127.0.0.1), a process also called "resolving."
This allows computers and other devices on the internet to find and communicate with each other using their unique IP addresses, which makes navigating the web much easier, as no one has to remember the long number sequences.
1 - Nameservers
Nameservers are important for resolution and have the following three main functions in DNS:
Name resolution: The translation of domain names into IP addresses and vice versa.
Forwarding and caching: If a name server doesn't have the requested information itself, it forwards the request to find the IP address and then caches it so that future requests can be processed more quickly.
Zone storage: DNS settings (or DNS records, resource records) are stored on name servers in so-called "DNS zones." For example, an "A record" translates a domain name (e.g.,
docs.internex.com) into an IP address (e.g.,127.0.0.1).
When resolving names, it's important to note that the name server that stores the original zone with the DNS settings is also called an "authoritative name server".
Name servers that only cache or forward the request are called "non-authoritative name servers".
A "recursive name server" or "resolver" receives requests and is responsible for finding the full IP address by querying other name servers.
2 - Zones
As already mentioned, the individual DNS settings (or DNS records, resource records) are stored in DNS zones on authoritative name servers. The following types of records exist, among others:
SOA records: contain binding information about a DNS zone
A records: convert a domain name to an IPv4 address
AAAA records: convert a domain name to an IPv6 address
CNAME records: convert a domain name to another name
TXT records: convert a domain name to text
MX records: convert a domain name to the FQDN of a mail server
SRV records: convert a domain name to IP services (including port and server)
and much more...
In the Domain Name System (DNS), when managing resource records on name servers, the full domain name (FQDN) must be specified with a dot at the end.