DNS Implementation

DNS (Domain Name System) Implementation:

  DNS is a Service or Protocol which is basically used to resolve fully qualified Domain name to IP Address & IP Address to fully qualify Domain Name. DNS provide hierarchical structure there are some sample of top level Domain

          .com     -  Commercial

          .net       -  Network

          .gov      -  Government

          .int        -  International

          .mil       -  Military

          .org      -  Organization

          .edu      -  Education

Domain Name    =  255 Characters longs
Computer Name =  63 Characters

Fully Qualify Domain Name = FQDN

FQDN = Computer Name.Domain Name

            = Server.test.com

Type of DNS Server

        1) Primary Server = Primary server create a copy of zone that can be updated directly on this Server.

        2) Secondly Server = Second Server also create a copy of zone that exist o an other server. This option is help balance the processing load of Primary Server & Provide fault tollerence it create a Read Only copy of zone.

     Stube Server(Zone) = This server create a copy of zone containing only name server (NS), Start of Authority (SOA) and possibly Glue, host(A) Recordes etc....

Type of DNS Zone

1) Forward Lookup Zone = Used to resolve fully qualified domain name to IP Address.

2) Reverse Lookup Zone = Used to resolve IP Addres to full qualified domain name (FQDN).

DNS Components

     DNS Components to configure the DNS Server.

        1) DNS Server = It is Computer that runs a DNS Server Service or bind Service.

        2) DNS Resolves = It is service that uses the DNS protocol to query information from DNS server. DNS Resolver communicate with either Remote DNS Server or the DNS server program running on the local computer.

        3) Resource Records = Resource Records are DNS Database entries that are used to answer DNS client query. Resource Record are describe as a specific record type such as:

            a) Host Address (A)

            b) MX Record (Mail Exchanger)

            c) PTR (Pointer Records)

            d) SRV (Service Location)

            e) CName (Alias)

            f) NS (Name Server)

            g) SOA

DNS Query Steps

      1) A name query begin at a client computer and is passed to the DNS client service for resolution.

      2) When the query cann't be resolve locally it will send to DNS server.

DNS Transport Protocol :

     DNS Resolver first attend to used UDP protocol for transport information if UDP fail it uses TCP protocol.