Here are some of the most commonly used DNS terms. Every beginner should understand them!
Domain Name System
Domain Name System (DNS) is a decentralized international system, and it is built in a hierarchical way with several levels. Its purpose is to link domain names to IP addresses (IPv4 and IPv6). Thanks to DNS, humans are not required to memorize long and difficult IP addresses. Instead, we simply use the domain names to connect to the various services.
Domain Name
The domain name is an identifier. It is a unique text string for naming different devices or services, for instance, Wikipedia.org. Humans are able to use it and remember it, which is a lot more comfortable than its IP address. There are two kinds of domain names – FQDN (Fully Qualified Domain Names) and PQDN (Partially Qualified Domain Name).
DNS zone
The DNS zone is the administrative piece that the DNS namespace uses. Each DNS zone is controlled by a separate DNS administrator. For that reason, the DNS system is viewed as decentralized. Oftentimes, a domain name and the DNS zone are mistaken as the same thing. Yet, that this is not correct. One domain could hold just a single DNS zone. However, other cases are usually more common. When a domain has several DNS zones, it is easy to understand that they are not equal.
The DNS zone stores a lot of different data and DNS records. Besides, inside the SOA (Start of Authority) record is kept contact information about the administrator and several zone parameters.
DNS query
DNS query is called the process of searching the IP address (an A record or an AAAA record) or different DNS records of a domain. When a user requests the data it needs, it triggers the DNS query, and it is taken by a DNS recursive server.
DNS record
DNS records are simple text files that hold important information about DNS. Usually, one domain can have multiple DNS records. Each of them indicates various settings for a domain. The DNS records are kept in a zone file that every DNS zone has.
Here are some of the popular DNS records:
- SOA record – holds important details about the zone.
- A record – Links a domain to an IPv4.
- AAAA record – Links a domain to an IPv6.
- CAA record– Holds a list of permitted Certification Authorities (CAs) for the domain.
- MX record – Points to the email server accountable for receiving emails for the domain.
- CNAME record – Links one name to another.
- NS record – Points to the authoritative name server for the domain.
- PTR record – IPv4 or IPv6 to a domain.
- TXT record – Different uses, like domain authentication.
DNS server
DNS servers are divided into two essential types – authoritative name servers and recursive name servers.
The authoritative name servers hold the zone file of a particular zone. They have the ability to answer DNS queries. Such types of servers are all the authoritative name servers for each domain, like TLD servers and Root servers.
Recursive name servers are responsible for searching for the answer to the DNS query. They travel and query different servers until they obtain a response.
Dynamic DNS
The benefit of having Dynamic DNS (DDNS) is it automatically updates and changes the host’s IP address.
The traditional DNS connects the domain name to IP address via A or AAAA DNS records. Dynamic DNS makes sure that even if the ISP changes the domain name’s IP address, the user is still going to be able to reach it.
Dynamic DNS is very simple to use and, in addition, is a very beneficial service.
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