Dynamic Host Configuration Protocol - DHCP - Introduction

DHCP? Hm... Well I think I heard this term somewhere... Yes, yes I have, but what is it, what is its main purpose?

Well, we are most glad to offer You explanation of DHCP. Its name, purpose and mechanism behind it. DHCP stands for Dynamic Host Configuration Protocol, this protocol isn't mandatory for your network to operate properly, but it's hell lot easier to have it configured in your network, specially if you have lot of computers and devices.

We know that almost every device in IP network has IP address assigned, there are two ways to assign that IP address to device. First is manually, but this isn't convenient when you have hundreds of computers in network and second is automatic via DHCP. There are few more protocols like BOOTP, but this is obsolete protocol and predecessor of DHCP.

DHCP enables your clients just to connect their computers, laptops, PDAs, smart phones, etc. to switch, patch panel, wireless access point, providing them with IP address that is available. There is no concern about IP address mismatch, collision and so on. NOTE: This is how DHCP works, but often (and for reason) there are other security mechanisms which prevent unauthorised access to network.

DHCP works on port numbers 67 and 68 over UDP. This port numbers are borrowed from BOOTP, 67 for DHCP server communication and 68 for communication with clients, after introduction of DHCPv6 (for IPv6 addresses) the new port numbers were introduced, 546 and 547.

DHCP can provide much more than just IP address, like Default gateway, DNS information, and so on. These are called DHCP options. In next parts of DHCP series, we will explain how DHCP works, we will provide example configuration of DHCP server on Linux and MS Server, example topologies...

Until next tutorial, see ya! :)