Domain Name and IP Address
Each electronic device which is involved in communication has got MAC address. MAC Address is unique for each device i.e no to devices can have same MAC address. MAC address is generally in the hexadecimal form like 00:0A:BC:9F:E0:11. MAC address for a particular device is assigned by the manufacturer and can not be changed further. We can access the device if MAC address is known. But practically it is not feasible.For example: Daily we surf internet and access different web servers. If daily we access 50 or 60 web server then it is not feasible to us to remember all the hexadecimal MAC address.
Instead of using MAC address we can use IP addresses. IP addresses are rather easy to us than MAC addresses.
Just like MAC addresses each device can be assigned an IP address. Unlike MAC address, different IP address can be assigned to the same device at different time. But in a working network IP address is unique i.e no two devices can have the same IP address. If any conflict is there then the devices may not use the network. Therefore it must be ensured in a network that all the communicating devices are assigned unique IP addresses.
IP address can be assigned to the device in two ways. First method, all the devices can be manually assigned an IP address. If the network is small then we can assign IP address manually. If the network is large then, manual method will not be feasible as there is a risk of assigning same IP to two or more devices. If the same mistake is committed then it will take much more time to resolve the issue as we have to check all the devices.
Second method is more efficient. We can use DHCP server for the purpose. DHCP server automatically assigns IP address to devices. And the margin of error is reduced. No two devices will get same IP address from the DHCP server.
Again IP address may be local or public. Local IP addresses are those which are used inside LAN. The local IP address can't be accessed from outside the LAN. Public IP addresses are those which can be accessed from outside the LAN.All the web servers use public IP addresses.
In the above section we discussed about MAC address and IP Address. Using IP addresses alone to access the web servers is not feasible. More than millions of web servers are available and hence for us it is easy for us to remember the IP addresses of the web servers with which we are used to. So to solve the issue, domain name is used for each web server. Because for human being remembering a name is easy than to remember large numbers. This name used for the web server is called domain name. All the domain names are managed by domain name server or DNS.
How we access a web server ?
Suppose a client host wants to access a remote web server, say google. Both are in two different networks.When the client host is trying to access google.com, the client host have to resolve three issues:
1. How to access the remote network ?
2. How to access remote host in the remote network ?
3. How to access the desired process for google in the remote host in the remote computer ?
The solution is in the IP Address. First of all the domain name is converted to the corresponding IP Address by DNS server. The DNS server maintains all the domain name and the corresponding IP Addresses.
IP adress consists of two parts: Network ID and Host ID. By using Network ID the client can reach to the remote network. By using the host ID the client can go to the remote host in the remote network. And to get to the process in the remote host in the remote network port number is used
Data communication is the process in which the sender send data to the receiver over some communication medium. For successful data communication both the sender and the receiver should in the same network. LAN or Local Area Network is collection of different communicating devices connected through communication medium.
In a LAN when a sender wants to send data to a receiver, several questions arises. Like
How the sender will identify the receiver ?
How the receiver will identify the sender ?
and so on..
In this article we will try to get answer to the above two stated questions.