What is DNS – Domain Name System – DNS Protocol – DNS Resolver

DNS is the abbreviation of Domain Name System which is a stratified naming system for services, computer and for any other possessions attached to the network or internet. DNS (Domain Name System) is responsible to links a variety of information with domain names allocated to each of the participants. The main task of DNS (Domain Name System) is the translation human language into the binary code. It is also serve as the distributed database that offers mapping among Internet Protocol addresses and host names. DNS makes facilitate the client to consign a domain name to groups of internet users in a significant way.

The DNS (Domain Name System) share out the conscientiousness of conveying domain names and mapping those names to IP addresses by delegating trustworthy name servers for each domain. Authorized name servers are consign to be accountable for their exacting domains, and then allocate other reliable name servers for their sub-domains. This method has through the DNS (Domain Name System) circulated and error understanding and has helped keep away from the need for a single central register to be constantly asked and updated. Usually domain name system restores different types of data such as mail server list that recognize email for a specified internet domain. In short DNS (Domain Name System) is a compulsory part of the functionality of the internet.

DNS Protocol

The DNS protocols contain various kinds of DNS messages that are progressions according to the data in their message fields. DNS protocols consist of message type which consists of queries; updates, and responses, DNS (Domain Name System) query message format has fixed length which is 12 bytes. DNS Header has fixed length and all other such as Question Entries, Answer Resource Records, authority Resource Records, Additional Resource Records have variable length. There are many other type of DNS (Domain Name System) messages or protocol such as DNS query message header, DNS query question entries, DNS resource records, Name query message, Name query response, Reverse name query message, DNS update message format, DNS (Domain Name System) update message flags, Dynamic update response message.

DNS resolvers

The DNS (Domain Name System) client side is called DNS resolver which is responsible for starting and sequencing the inquiries that eventually guide to a complete resolution of the sources required. DNS resolvers and DNS server are performing recursively on behalf of the resolver.

Resolving typically involve iterating through numerous name servers to locate the desirable information. Some resolvers purpose simplistically and can converse only with a particular name server and these all called stub resolvers which are rely on a recursive name server to execute the work of finding information for them.

DNS related files

DNS (Domain Name System) consist of boot which is a BIND boot configuration file, Cache.dns use for uploading, Root.dns which is a root zone file, and zone_name.dns which is a used when any zone entered and configured for a server.

DNS Resource Records

DNS Resource Records contains alphabetic list such as A which is a Host address (A) resource record, AAAA which is a IPv6 host address (AAAA) resource record, AFSDB which is a Andrew File System Database (AFSDB) resource record, ATMA which is a Asynchronous Transfer Mode address (ATMA) resource record, CNAME which is a Canonical name (CNAME) resource record, HINFO which is Host information (HINFO) resource record, ISDN which is a Integrated Services Digital Network (ISDN) resource record, KEY which is a Public key resource record, MINFO which is a Mailbox mail list information (MINFO) resource record, MX which is a Mail exchanger (MX) resource record, NS which is a Used to map a DNS (Domain Name System) domain name, etc.

DNS Architecture

The DNS Architecture consist of the following

Domain name space

Domain name space included a hierarchy of domain names and every node has zero or many source record having information linked with the domain name. The domain name space tree divided into zones starting at the root zone. A DNS zone contains of a compilation of linked nodes convincingly served by authorized name server because a single zone can host multiple server at a time.

Domain name formulation

Domain name formulation contains one or many parts which is technically called labels that are usually concatenated, and surrounded by dots. The right label express the peak level domain and it move down from right to left .every label to the left side classify a subdivision of the domain to the right. Each label has 63 characters and not surpasses a total length of 253 characters. Technically contains character signify as octet. The ASCII characters are allowed and included A to Z and 0 to 9, and hyphen. It is called LDH rule. The domain name relate as a minimum one IP address.

Internationalized domain names

The allowable character set of the DNS prohibited the demonstration of names and words of a lot of languages in their inhabitant alphabets or scripts. The IDNA system has approved by ICANN which diagram Unicode strings into compelling DNS character set. ICANN accepted the installation of IDN country code domain.

Name servers

The DNS system is upholder by a dispersed database system. This system employs the client server model and the knobs of database are the name servers. Every domain has minimum one authorized DNS server which distributed information about domain and name server of every domain subsidiary to it.

Authoritative name server

It is a name server which is responsible to answer about the configuration that it is held by an original source. Only Authoritative name server returned answer to inquiries related to domain name that have been exclusively configured by the administrator. Authoritative name server can be whichever slave master which uses an automatic method of the DNS protocol in contact in the company of its master server which maintains alike copy of the master account. Each zone of DNS ought to be a set of authoritative name servers. After the registration of domain name their setting up has need of the assignment of a primary name server and minimum one secondary server. The necessity of manifold name servers intends to make the domain still practical yet if one name server happen to unreachable or untreatable. The title of a primary name server is exclusively resolute by the precedence specified to the domain name registrar. For this reason usually only the completely competent domain name of the name server is compulsory.

Recursive and caching name server

The authorized name servers are enough for the process of the Internet. While with the authoritative name servers working Each DNS inquiry should start with recursive inquiries fro the root zone and every user have to employ resolved software competent of recursive operation. The effectiveness can be improved by dropping DNS traffic across the internet and boost performance in end user. DNS cache servers also supported by Domain name system which has ability to store information for a long period resolute in the configuration and these caching DNS server also called DNS caches. The amalgamation of DNS caching and recursive functions in a name server is not obligatory. These all can be put into practice separately in servers for particular reasons. All ISP commonly offer caching and recursive name servers for their client.

DNS and Active Directory

The active directory of windows server uses DNS as its domain manager location system. For any type of task such as updating, authentication, searching etc any computer based on window server use DNS to allocate domain controller of active directory and all these domain controller use DNS to trace each other.


The previous means of name declaration for a Windows network was WINS. DNS is unlike than WINS because WINS is flat and DNS is hierarchical name space. Those clients and application rely on NetBIOS prolong to use WINS for name declaration. WE can get maximum competence by the mixture both WINS and DNS for a variety of network resources and services.


For DNS server of Widows the DHCP service offers default carry to register and update information for inheritance DHCP clients in DNS sector. DHCP integration facilitate a DHCP client that is incapable to dynamically update DNS sources records straightforwardly to have this information updated in DNS onward and undo lookup zones by the DHCP server.

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