Domain Name Services And IP Addressing

Domain Name Services Domain name is a way to identify and locate computers connected to the Internet. No two organizations can have the same domain name. A domain name always contains two or more components separated by periods, called dots(“.”) Once a domain name has been established, ”Sub domains "can be created within the domain. The structure for this is: Hostname.subdomain.second-leveldomain.top-leveldomain

(Cont….) DNS as a whole consists of a network of servers that map Internet domain names like to a local IP addresses. DNS enables domain names to stay constant while the underlying network topology and IP address change. Each domain name corresponds to numeric IP addresses. The Internet uses the numeric IP address to send data.

For instance, – You may be connecting to a World Wide Web server with the domain name but as far as network is concerned, you are connecting to the web server with the IP address associated with that domain name.

Domain Name System completes the task of matching the domain names to IP addresses. Domain names and their corresponding IP addresses, must be unique. Domain Name System is a collection of databases that contain information about domain names and their corresponding IP addressing.

(Cont….) Domain Name Servers are computers that translate domain names to IP addresses. This system allows the Internet users to deal with the more intuitive domain names, rather than having to remember a series of numbers. Domain name space is a hierarchical,tree structured name space, starting at an unnamed root used for all DNS operations. In DNS name space, each node and leaf in the domain name space tree represents a named domain. Each domain can have additional child domains.

There are three components of DNS: – Resolver – Name server – Database of resource records(RRs)

There are several levels of domains: – Top level Domains  Country Code Top Level Domains(.uk,.in,.us)  Generic Domains (.com,.gov,.edu etc)  Infrastructure Domain(.arpa) – Root Level Domains – Second Level Domains

IP Addressing It is an unique,numeric identifier used to specify a particular host computer on a particular network, and is a part of global, standardized scheme for identifying machines that are connected to the Internet. There are two types of IP: – IP version 4(IPv4)-32 bit – IP version 6(IPv6)-128 bit

(cont….) IP is basically the set of rules for one network communicating with any other Static & Dynamic IP address Relationship with Physical Address IP address has two parts: – The identifier of a particular network on the network on the Internet(net id) – An identifier of the particular device(host id)

There are 5 classes for IP address: – Class A – Class B – Class C – Class D – Class E

ClassRangeOrder Bits N/w or HostDefault Subnet Mask A0-1270N.H.H.H B N.N.H.H C N.N.N.H D Reserved for Multicasting E Used for research

ClassNumber of NetworksHosts per Network (Usable Addresses) A126( ) ( ) B16382( )65534( ) C (2 21 – 2)254(2 8 – 2)

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