Monday, 5 September 2016

What is DNS Server



Virtually every computer requires a mechanism to resolve name to IP addresses.

This requirement arise because IP address consist of four groups of number (Version 4, Version 6 consist 6 groups) and can be difficult for people to remember. People are tending to connect to network services by specifying a name. These names are called hostnames, and each machine is assigned one. Groups of these hosts form a domain. The software that translates these names to network addresses is called the Domain Name System (DNS).

Before Server 2000 NetBIOS (Network Basic Input/output System) names were used to identify computers, services, and other resources on Windows-based machines. In the early days of Windows networks, LMHOSTS files were used for NetBIOS name resolution.

With Windows 2000 and Windows Server 2003, hostnames are used instead of NetBIOS names. In a Windows Server 2003 domain, DNS is used to resolve hostnames and locate resources such as network services.

To support earlier version in Server 2003 both NetBIOS and DNS coexist. These naming systems are not related with each other so they require separate configuration to resolve their name to IP address.

Earlier versions of window still rely on NetBIOS names to communicate with other hosts on a network. A NetBIOS name is a 16-character name where the first 15 characters identify a unique host and the 16th character identifies a service or application running on the host such as the Workstation or Server service.

Differences between NetBIOS and DNS

DNS is a naming system that allows people to use names instead of IP address. Names are then translated automatically into IP addresses that computers use to locate each other and to communicate.

NetBIOS is an API (application programming interface) used in earlier version of windows that allow computers to connect and communicate.

NetBIOS use 16-character name while DNS used 255 character names.

NetBIOS use flat name while DNS use hierarchical name.

  • NetBIOS Name :- NetBIOS names are the name which you assign the computer during the installation. NetBIOS computer names are 15 characters, whereas NetBIOS service names are 16 characters. First 15 characters of the NetBIOS service name are the same as the host name. Last sixteenth character is used to identify the specific NetBIOS services.
  • Host name:- First part of FQDN. For example first part of the FQDN system1.example.com is system1. Host name is also known as computer name.
  • FQDN :- FQDN is a unique DNS name that indentifies the computer on the network. You can understand it as concatenations of the host name, primary DNS suffix, and a period.

Illustration of FQDN


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