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DHCP protocol and distribution of IP in a network

Posted on December 21st, 2008 by Deepak

As an engineering student or computer science enthusiast you might be curious to know about how the IP addresses are allocated and managed inside any network. You would definitely want to know the reason why sometimes your Host part of IP address changes within a network. We all know that each machine that can connect to the Internet must have a unique IP address. This IP address is assigned when an Internet connection is created for a specific computer. Now, for every computer in the organization either you have to enter the IP addresses manually or it can be done automatically and managed dynamically. But manual configuration would be tedious task for even medium or large size network. This is where DHCP’s role comes into play. DHCP (Dynamic Host Configuration Protocol) is a communications protocol. DHCP lets network administrator to centrally manage and automate the assignment of IP addresses in an network. This protocol lets to supervise and distribute IP addresses from a central point. whenever a computer is plugged into a different place in the network it automatically sends a new IP address. DHCP leases the IP addresses for some fix amount of time. The default lease time is one week. This lease time may vary also. For those computers which need permanent IP addresses like Web servers etc static addresses are allotted.

The protocol has been designed so that it can it can dynamically reconfigure networks in which there are more computers than there are available IP addresses and where the users change frequently. Actually, DHCP is an extended protocol from BOOTP i.e. Bootstrap Protocol. Though the working of both the protocols are similar but BOOTP is not dynamic. Both the protocols are based on server – client architecture. BOOTP and DHCP clients sends requests to their respective BOOTP and DHCP servers. Both DHCP and BOOTP uses Relay machine which knows the address of DHCP or BOOTP servers. Hence they forward the request from DHCP or BOOTP clients to their respective servers.