DNS means Domain Name System, is a hierarchical distributed naming system for computers, services, or any resource connected to the internet or a private network.

  • The DNS converts the hostnames to the IP addresses and vice-versa.
    The DNS can be quickly updated, allowing a service’s location on the network to change without affecting the end users.
  • The DNS distributes the responsibility of assigning domain names mapping those names IP addresses by designating authoritative name servers for each domain.
  • Name servers are assigned to be responsible for their supported domains, and may delegate authority over subdomains to other name servers.
  • The DNS also specifies the technical functionality of the database service.
  • The DNS maintains the domain name hierarchy and provides translation services between it and the address spaces. Internet name servers and a communication protocol implement the DNS.

The below diagram shows how DNS will work.

A DNS name server is a server that stores the DNS records for domain name.

Records in DNS:

DNShave many records, in that some of the records are:

A Record(Host Address):

‘A’ record is an entry in dns zone file that maps each domain name or subdomain to the IP address .It specifies the IP address (IPV4-32 bits) to which the user would be sent for eachdomain or subdomain.

A DNS name server is a server that stores the DNS records for domain name.

AAAA Record (IPV6 host address):

‘AAAA’ record specifies the IPV6 address (128 bits) for given host. So it works the same way as the ‘A’ record and the difference is the type of IP address.

CNAME Record (Canonical Name for Alias):

‘CNAME’ record specifies a domain name which is used to resolve the original DNS query and it is used for creating aliases of domain names.

HINFORecord (Host Information):

‘HINFO’ record is used to get the information about the host and it gives the CPU type, OS details. It provides the possibility for the operating system to use the specific protocols when one host wants to communicate with other host. This record is not used in public servers because of security reasons.

MX Record (Mail exchanger):

‘MX’ record specifies the mail exchange for DNS domain name. Normally SMTP protocol is used for sending the mails between hosts. DNS have more than one mail exchange server and each one have their own priority.

NS Record (Name Server):

‘NS’ record contains the names of domains and subdomains. It specifies an authorative name server for the host.

PTR Record (Reverse-lookup Pointer Recodes):

‘PTR’ record is used for look up domain names based on IP address. In the above screen shot put ‘PTR’ instead of ‘NS’.

SOA Record (Start of Authority):

‘SOA’record specifies the core information about a DNS zone, server name, email of the domain administrator, domain serial number and timers relating to refreshing the zone.

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