DNS is a globally scalable, dynamic, hierarchical, and distributed database that gives us the provision of mapping between text records, IP addresses (both IPv6 and IPv4), mail exchange information, hostnames, security key information defined in Resource Records, and name server information. This information is also maintained and grouped into zones in the DNS server so that it can be accessed and globally retrieved through distributed architecture of the DNS. DNS can either use the Transmission Transfer Protocol (TCP) or the User Datagram Protocol (UDP). When the DNS server decides to use the UDP in transportation, it will have the capability to deal with the UDP sequencing and transmission.
The DNS has comprised of the hierarchical domain name space has the tree data structure of nodes (linked domain names). The DNS (domain name space) uses the Resource Records that may not exist to store the domain information. The tree data structure for the DNS commences at the root zone that is at the top DNS hierarchy level. The DNS root, although it has no display in the user application, is presented as a trailing dot.
Important DNS Terminology
To have a clear understanding of DNS and its terminologies, it is important that you must be familiar with the following terms:
Resolver: a DNS client that acts as the sender of the DNS messages to get information about the domain name spaces requested.
Recursion: This is used to refer to the action taken a query is needed from the DNS server on behalf of the resolver in the DNS.
Authoritative Server: This is the server that queries for the information needed from DNS query.
FQDN: this action stands for the Fully Qualified Domain Name. It is also referred to the absolute device name within the distributed DNS database.
RR: this is the Resource Record. It is also a format that is used by the DNS messages composed of the following: TYPE, NAME, RDLENGTH, CLASS, TTL, and RDATA.
Zone: This is a database that contains information about the DNS protection on the authoritative server.
Primary Functions of DNS
The main function of the DNS is to translate IP addresses to hostnames or hostnames to IP addresses. The DNS resolver accomplishes this translation process by sending the DNS query to the DNS server to request some information from the RR. DNS resolution processes include:
• If the server is authoritative, the DNS server will give a response message that contains RRs if it is not configured as a recursive resolver.
• The DNS server will inspect the locally stored RR information if the server is only configured.
• The DNS server will query the information contained in the request if the server is not authoritative.